Problem with prefix for inner join and output to file

Hello, I'm writing a store procedure that uses inner joins but for some reason I am getting the following error:

Server: Msg 107, Level 16, State 2, Procedure mw_aragedreceivables_sp, Line 206
The column prefix 'a' does not match with a table name or alias name used in the query.

Here is my code:

--  exec dbo.mw_aragedreceivables_sp 'MWHydrocarbon', '06/14/2006', NULL, NULL, ''


-- drop procedure mw_aragedreceivables_sp

CREATE procedure dbo.mw_aragedreceivables_sp
      @company            varchar(40),
      @dateto                  varchar(32),
      @fromcustomercode      varchar(8),
      @tocustomercode            varchar(8),
--      @sort_column              varchar(3),
      @territory_code        varchar(8),
      @days_aged            int = 0,
      @availableC            int = 0,
      @balance            int = 0

as
declare
      @dateto_jul            int,
      @year                 int,
      @month                int,
      @date                 int,
      @jul_date            int,
      @dateto_date            datetime


-- temporary table creation
create table #artrxage_tmp
(
      trx_type            smallint,
      trx_ctrl_num            varchar(16),
      doc_ctrl_num            varchar(16),
      apply_to_num            varchar(16),
      apply_trx_type            smallint,
      sub_apply_num            varchar(16),
      sub_apply_type            smallint,
      salesperson_code      varchar(8),
      territory_code            varchar(8),
      price_code            varchar(8),
      date_doc            int,
      date_due            int,
      date_aging            int,
      date_applied            int,
      amount                  float,
      cust_po_num            varchar(20),
      order_ctrl_num            varchar(16),
      customer_code            varchar(8),
      payer_cust_code            varchar(8),
      trx_type_code            varchar(8),      
      ref_id                  int,
      nat_cur_code            varchar(8),
      rate_oper             float,
      divide_flag             int
)

create table #finalvalues
(
      customer_code   varchar(50),
      customer_name   varchar(50),
      doc_ctrl_num    varchar(50),
      apply_to_num    varchar(50),
      apply_trx_type  smallint,
      date_doc        int,
      date_due        int,
      date_aging      int,
      date_applied    int,
      amount          float,
      salesperson_code varchar(50),
      territory_code  varchar(50),
      price_code      varchar(50),
      cust_po_num     varchar(50),
      order_ctrl_num  varchar(50),
      trx_type        smallint,
      trx_ctrl_num    varchar(50),
      trx_type_code   varchar(50),
      ref_id          int,
        nat_cur_code    varchar(50),
        rate_oper       float,
        oper_currency   varchar(50),
        divide_flag     int,
        company_name    varchar(50),
        dateto_jul      int,
        credit_limit    float,
      additional_credit float,
      age30_60      float,
      age60_90      float,
      ageover90      float,
)



create table #non_zero_records
(
      doc_ctrl_num varchar(16),
      trx_type smallint,
      customer_code varchar(8),
      total float
)  
create clustered index iv_npif_ind1 on #non_zero_records ( doc_ctrl_num, trx_type, customer_code )


create table #temp1
(
      code varchar(20),
)

create table #temp2
(
      c_id varchar(20),      
      e_code varchar(20),
      code varchar(20)
)  


-- initialise parameters
if (@dateto = '~null~' or @dateto = ''  or @dateto is null) select @dateto_date = getdate()
else select @dateto_date = convert(datetime,@dateto)

select  @dateto_jul = datediff(dd,'1900/01/01', @dateto_date ) + 693596

if (@fromcustomercode = '~null~' or @fromcustomercode = '' or @fromcustomercode is null) select @fromcustomercode = ''
if (@tocustomercode = '~null~'  or @tocustomercode = '' or @tocustomercode is null) select @tocustomercode = 'zzzzzzzz'

if (@territory_code = '~null~' or @territory_code = '' ) select @territory_code = null


-- finds non zero records
insert
  #non_zero_records
select
  a.apply_to_num ,
      a.apply_trx_type,
      a.customer_code,
      sum(amount)
from
  artrxage a
  inner join arcust c on a.customer_code = c.customer_code
where
  a.date_applied <= @dateto_jul and
  a.customer_code between @fromcustomercode and @tocustomercode and
  ( @territory_code is null or c.territory_code = @territory_code )
group by
  a.apply_to_num,
      a.apply_trx_type,
      a.customer_code  having abs(sum(amount)) > 0.0000001

insert into #temp1
select replace(replace(left(customer_code , 15 ), 'AR', ''), 'CUS', '')
from artrxage

insert into #temp2
select company_id, epicor_code, code from core..company_epicor_xref b
inner join #temp1 u on u.code = b.epicor_code
order by epicor_code


-- inserts data for non zero records
insert
  #artrxage_tmp
select
  a.trx_type,
      a.trx_ctrl_num,      
      a.doc_ctrl_num,      
      a.apply_to_num,      
      a.apply_trx_type,      
      a.sub_apply_num,      
      a.sub_apply_type,      
      a.salesperson_code,      
      a.territory_code,      
      a.price_code,      
      a.date_doc,      
      (1+ sign(sign(a.ref_id) - 1))*a.date_due + abs(sign(sign(a.ref_id)-1))*a.date_doc,
      (1+ sign(sign(a.ref_id) - 1))*a.date_aging + abs(sign(sign(a.ref_id)-1))*a.date_doc,
      a.date_applied,      
  a.amount,
      a.cust_po_num,      
      a.order_ctrl_num,      
      a.customer_code,      
      a.payer_cust_code,      
      '',
      a.ref_id,
  a.nat_cur_code,
  a.rate_oper,
  1
from
  artrxage a,
  #non_zero_records i
where
  a.apply_to_num = i.doc_ctrl_num and
  a.apply_trx_type = i.trx_type and
  a.customer_code = i.customer_code and
  a.date_applied <= @dateto_jul


-- updates transaction type description
update      #artrxage_tmp
set       trx_type_code = b.trx_type_code
from       artrxtyp b
where       #artrxage_tmp.trx_type = b.trx_type


--updates divide_flag for multi-currency conversion
update      #artrxage_tmp
set  divide_flag = m.divide_flag
from #artrxage_tmp a
inner join pltmaster..mccurate m on a.nat_cur_code = m.from_currency
inner join glco g on g.oper_currency = m.to_currency


--report selection
insert into #finalvalues
select distinct
      t.company_id,
      t.max(expiration_date) as expiredcredit_limit,
      t.e_code,
        a.customer_code,
      c.customer_name,
      a.doc_ctrl_num,
      a.apply_to_num,
      a.apply_trx_type,
      a.date_doc,
      a.date_due,
      a.date_aging,
      a.date_applied,
      a.amount,
      a.salesperson_code,
      a.territory_code,
      a.price_code,
      a.cust_po_num,
      a.order_ctrl_num,
      a.trx_type,
      a.trx_ctrl_num,
      a.trx_type_code,
      a.ref_id,
        a.nat_cur_code,
        a.rate_oper,
       g.oper_currency,
        a.divide_flag,
       g.company_name,
        @dateto_jul as dateto_jul,
        c.credit_limit,
      isNull((select sum(amount) from core..v_company_additional_credit where epicor_db_name = 'MWHydrocarbon' and status = 'A' and @dateto between effective_date and expiration_date and epicor_code + 'AR' = a.customer_code), 0) as additional_credit,
      case when (@dateto_jul - a.date_aging) between 30 and 60 then amount else 0 end as Age30,
      case when (@dateto_jul - a.date_aging) between 60 and 90 then amount else 0 end as Age60,
      case when (@dateto_jul - a.date_aging) > 90 then amount else 0 end as Age90
      
from
  glco g,
  #artrxage_tmp a,
  core..company_additional_credit t
  inner join arcust c on a.customer_code = c.customer_code
  inner join #temp2 x on x.c_id = t.company_id
  Group by company_id, e_Code
 
   
select * from #finalvalues

/* select customer_code, credit_limit, additional_credit, customer_name,
          (credit_limit + additional_credit) - sum(amount) as balance ,    
          sum(Age30_60)  as   Age30_60 ,    
          sum(Age60_90)  as   Age60_90,        
          sum(ageover90) as   Ageover90
from #finalvalues
group by customer_code, customer_name, credit_limit, additional_credit */

drop table #artrxage_tmp
drop table #finalvalues
drop table #non_zero_records
drop table #temp1
drop table #temp2

GO

I believe that although the query says that the error is coming from the following line I believe the error is coming from huge select at the end of the file in the from section. Also, wants I get this to work I want output the data to a file in a delimeter file. Can someone help me with these two things. I need this info ASAP for a work project.