Real Real real SImple question!

how could I make a 'if not equal then message box an error' in this part of the program

Private Sub Command1_Click()
MP.FileName = File1.Path + "\" + File1.FileName
MP.Play
End Sub

Are you after something like

If MP.Filename <> sFileName then
Msgbox Error.mEssage,vbcritical,Gee a Heading
do whatever
End If

Need more explanation.............