There are various reasons for the values not to match:
Have any journals been posted directly to the control account?
Use the transaction enquiry to search for transactions in the control account not from the sales ledger.
Have your Analysis codes been set up correctly to use the Sales control? If they are not correctly debiting or crediting the Purchase Control account then this will cause differences.
Compare the transactions in the control accounts with the Sales ledger for the same period to identify any differences in value.
Are you comparing the 'Aged Debtors as at Date' report to the 'Aged Debtors as at Period' Report? These reports will potentially show different information due to Transactions dates not necessarily reflecting the period and years they have been posted to.
Are the Sales Ledger and the Nominal Ledger in the same year?
if the Sales ledger has been moved forward then you may need to run the 'Aged Debtors as at Period' Report in Last year 12 to compare it against the Nominal in Current year 12.
If your issue is that individual aged reports in a subledger database do not match, but totals do, please see the article Multi Company aged reports do not balance by entity .
If the above does not assist in solving the problem then please raise a new case online and reference the title of this article and please include details of the customer affected and the values on the report and the customer account.