SQL - Undeclared scalar table variable

declare @DifferenceTable  table (
        DataAreaId nvarchar(10) ,
        SalesId nvarchar(50) ,
        InvoiceId nvarchar(50) ,
        ItemId nvarchar(50),
        InvoiceQty decimal(16,4) ,
        InventoryQty decimal(16,4)
    )




insert into @DifferenceTable (DataAreaId , SalesId , InvoiceId , ItemId , InvoiceQty ,  InventoryQty )
    select CustInvoiceTrans.DATAAREAID , CustInvoiceTrans.SALESID , CustInvoiceTrans.INVOICEID , CustInvoiceTrans.ITEMID , sum(CustInvoiceTrans.QTY) , 0. as InventoryQty
    from CustInvoiceTrans with(nolock)    
    group by CustInvoiceTrans.DATAAREAID , CustInvoiceTrans.SALESID , CustInvoiceTrans.INVOICEID , CustInvoiceTrans.ITEMID


update @DifferenceTable
    set InventoryQty =  tt.Qty from
                                           (select sum(InventTrans.QTY)*-1 as Qty , InventTransOrigin.DATAAREAID , REFERENCEID , InventTrans.INVOICEID , InventTrans.ITEMID
                                            from InventTransOrigin
                                             left join InventTrans      on InventTrans.INVENTTRANSORIGIN = InventTransOrigin.RECID
                                                                                    and InventTrans.DATAAREAID = InventTransOrigin.DATAAREAID
                                                                                    and InventTrans.ITEMID = InventTransOrigin.ITEMID
                                             where REFERENCECATEGORY = 0
                                             group by InventTransOrigin.DATAAREAID , REFERENCEID , InventTrans.INVOICEID , InventTrans.ITEMID
                                            ) tt
                                    where  @DifferenceTable.DataAreaId =  tt.DATAAREAID and @DifferenceTable.SalesId = tt.REFERENCEID
                                    and tt.INVOICEID = @DifferenceTable.InvoiceId and tt.ITEMID = @DifferenceTable.ItemId  


select * from @DifferenceTable