Sorry, I'm back again.

I've written a user-defined function to replace the often confusing
V/HLookup(...Match(...) .) combination used in spreadsheets to return an
element in a bordered (top and left edges) table. Here's the code:

Function GETENTRY(atRow As Variant, _
atCol As Variant, _
inTable As Range) As Variant

Dim i As Integer, j As Integer

On Error Resume Next
With Application
i = .Match(atRow, inTable.Columns(1), 0)
j = .Match(atCol, inTable.Rows(1), 0)
End With

If Err < 0 Then
MsgBox "One of " & atRow & " or " & atCol & " _
not found.", vbCritical
GETENTRY = CVErr(xlErrNA)
Exit Function
End If

GETENTRY = inTable(i, j)

End Function

Here's the problem: It works fine if invoked directly, but if I use Excel's
Paste (Insert) function dialogue box, then as soon as I click on the top
left corner of the range for the 3rd arg (inTable), it triggers the error
message.

(Actually, it doesn't exit the function as I expect either, instead it
flashes the message and waits for new input. Hitting the cancel
button on the dialogue box triggers the message again. But that's
a whole nuther confusion and I don't want to get side-tracked.)

I can avoid this outcome in 3 ways:

a) enter one of the other two args as the last one specified in the dialogue
box,
b) remove the On Error Resume Next statement, or
c) and this is really wierd, remove the MsgBox statement.

Choice a) is clearly not reasonable - I can't expect others to know that
trick - and choices b) & c) frustrate my *truly wonderful* error handling.

('course, the only reason I found out about this bug is that I was so
excited to see Excel list MY FUNCTION that I just had to try it. Hubrous
was my downfall.)

I'm really confused about this, especially the REM'ing out the msgbox part.
Does anyone have any idea about what's going on.