Filtered search not working

I have two sets of DataAssist pages - the first list is an accountants database, the second is a database of those accountants' clients. There's a link on the Accountants' list page to view each accountants' clients. The problem is that the Search function on the clients page isn't working - whatever you search for, it returns zero results. I've copied the PHP code at the foot of the page to see what the query is actually returning, and it looks like it's losing the variable I've set to view the clients by AccountantID:

Before searching:

SQL: SELECT ClientID, ClientName, StagingDate, accountants.AccountantID, clients.AccountantID, FirmName FROM clients JOIN accountants on clients.AccountantID = accountants.AccountantID WHERE clients.AccountantID = 28 ORDER BY StagingDate DESC

After searching:

SQL: SELECT ClientID, ClientName, StagingDate, accountants.AccountantID, clients.AccountantID, FirmName FROM clients JOIN accountants on clients.AccountantID = accountants.AccountantID WHERE clients.AccountantID = -1 ORDER BY StagingDate DESC

I also included a Clear Search behavior and that's not working either. Can I send you a link to take a look and see what I've done wrong? I should say that on the Accountants list page, the search and clear search functions are all working fine!