It does not seem (from the information you have provided) that you are having a problem with Cashbook in so much as you are having a problem with either your banks as defined in ACCPAC A/P or with your Macros as defined in the ACCPAC Plus Windowing System Manager.

Does your client experience a problem or receive errors in Cashbook?

Some more information may be helpful.

Perhaps some of these suggestions may help to determine where the actual problem lies...

1. If they are using Cashbook with G/L - check the Cashbook Company Profile (2nd screen) to ensure that the 'Bank Account' matches a valid G/L account for the bank you are using in your G/L program. Pressing the down-arrow on this field should bring up a list of chart of accounts if you are integrated with G/L.
2. Check the 4th screen in the Cashbook Company Profile to ensure that the 'A/P Bank Code' actually matches the one used to process the checks - and that this Code actually exists in A/P's 'Housekeeping - Add/Modify/Delete Banks' area.
3. If you can see the correct Bank in the area above, edit it to ensure that the 'General Ledger' fields display valid G/L Accounts for the Bank and Bank Error fields.
4. Lastly, if you have upgraded from a prior version of A/P - you may need to modify your macro if the menu options have changed at all from the earlier version.

Hope this helps!