Catastrophic failure using FindFormFieldB

I'm using FindFormFieldByTitle to see if a form contains a field of 'AgentName'.  It works for previous 20 fields, but when it gets to this field, it gets the following error:

Set AgentName error '8000ffff'

Catastrophic failure

/pw/digsi/di_gsi_process.asp, line 94

I have verified that this field does exist in the form (page 5 of 8).

Here's the section of code that's being executed:

for each item in dFormField
  fncDebug("<br>Set  <b>" & item)
  fieldIndex = QP.FindFormFieldByTitle(item)           'Line 94
  if fieldIndex > 0 then
   result = QP.SetFormFieldValue(fieldIndex,dFormField(item))
   fncDebug("</b> = <b>" & dFormField(item) & "</b>  Result: " &  result)
   fncDebug("<br>Flatten <b>" & item)
   result = QP.FlattenFormField(fieldIndex)
   fncDebug("</b>  Result: " &  result)
  else
   fncDebug("not found")
  end if
 next

Has anyone encountered this problem before or have any suggestions?

Thanks!