OK,
It appears it is down to having a filter remaining in your composer subform which was something along the lines of Lookup.Composer = 'b'. Actually
([Lookup_ComposerID].[Display]="b")
I removed that filter and now that search works for me.
I also amended the code of the requery before I did that, as i was not sure you can requery a subform control?
Code:
Private Sub btnSearchCatNumber_Click()
Dim strCatNumber As String
strCatNumber = InputBox("Enter Catalog Number", "Catalog Number", TitleNumber)
If strCatNumber = " " Then
Exit Sub
End If
Me.Filter = "TitleNumber = """ & strCatNumber & """"
Me.FilterOn = True
Me.subfrmSongsB.Form.Requery 'Added Form property?
End Sub
Edit: I put the code back as it was and it still searches successfully.