Filtering and "No current record" error

Hi all,
   When I use the OnFilterRecord event to filter records in a table I get
the desired result, but when I go to edit the record I get a "No current
record" error message.  Editing may then (usually) proceed.  If I set the
table's Filter property (to obtain identical results) and do not use the
OnFilterRecord event, I do not get this error message.  Does anyone know why
this happens?  I display the records in a read-only DBGrid, and the records
are then edited on a different form with standard data-aware controls
connected to same datasource as the DBGrid. Using Delphi 5 and Dbase IV