First of all thanks so much for your replies.
I'm not really showing any detailed information concerning the invoice just the amount billed, amont paid, and the total due. the detail payments are always hidden.
The IsNull({table.payment code}) or not ({table.payment code} in ["R", "E"]) got me real close. But the strange thing is that if I reverse it and do the payment code in ....or is null the invoices with no payment disappear again. Strange huh!. So, I can now produce a listing of all invoices regarless of total due and regardless if payments have been made. Thats great and definately a step in the right direction. Now, to only show those where a we have something due.
MY report is grouped by Comapny ID and Service Date, each unique pair is an invoice. Total billed is defined as Admin fee + Setup Fee. Total paid is defined as sum(payamt) where my paycodes are filtered as suggested. Total due is defined as total billed - total paid. If I try and do a group selection where total due <> 0 I get an error saving it can't be calculated until later, IF I use total billed - total paid which is the same as the formula for total due the condition is excepted and works fine if I runit for a single company. When I open it up to all companies the group selection is only applied to the one compnay I have been testing with. All invoices for all other companies are shown regarless of total due. What's up with that? I was filtering to the one company at the records selection level whic is where I put the payment code selection. CAn Record slection and Group selection be used together?