UNION query problem

hi i have this question on the go:

https://www.experts-exchange.com/questions/22474564/Query-Management-Getting-reults-from-two-queries-tables-into-one.html

but i'm stuck, and have spent the last 2 days trying to get this query to work, i'm close but i'm not there.

i need to link 4 tables:

Suppliers
Deliveries (all deliveries made by a supplier)
Complaints (all complaints raised against supplier)
Periods

i want to output a query showing a by month summary of supplier performance

looking like:
Month         Deliveries      OnTime      AvgLeadTime       Complaints
Jan2007          86                 80                  12.1                     2
Feb2007           0                   0                                               0
Mar2007          10                  10                   8.0                     0

now this needs to be generated for all suppliers regardless of whether we had delivieries or not, i.e a LEFT JOIN on tSuppliers
and i need to UNION ALL the tDeliveries and tComplaints
and then do a BETWEEN on the Period table

if that makes any sense! its 8pm here and i'm weary of this!

please help

i'm using:

SELECT l.sAcc, tP.Period, Sum(l.Deliveries) AS SumOfDeliveries, Sum(l.[On Time]) AS [SumOfOn Time], Sum(l.LeadTime) AS SumOfLeadTime, Sum(l.Complaints) AS SumOfComplaints
FROM [SELECT qDel.sAcc, Format([DueDate],"yyyy-mm") AS Period
, Count(qDel.Prod) AS [Deliveries]
, Sum(qDel.OnTime) AS [On Time]
, Avg(qDel.LeadTime) AS [LeadTime]
, 0 as Complaints
FROM qDel
GROUP BY qDel.sAcc, Format([DueDate],"yyyy-mm")
UNION ALL
SELECT tblSC_Report.Account, Format([Date],"yyyy-mm") AS Period, 0 , 0 , 0, Count(tblSC_Report.ComplaintNo)
FROM tblSC_Report
GROUP BY tblSC_Report.Account, Format([Date],"yyyy-mm")
]. AS l, tP
WHERE (((l.Period) Between [tp].[pfrm] And [tp].[pto]))
GROUP BY l.sAcc, tP.Period
ORDER BY l.sAcc, tP.Period;

see the other post, for examples of what worked and didnt.

Thanks G

i'm using Access 2003 and my experience (nor brain power!) is that high