When box is not filled in, don't let user save

Hi,

I have this code for a button:

Private Sub Details_GotFocus()
If [Sample Name] = Empty Then
MsgBox "You cannot save anything in Details", vbOkay
Else
DoCmd.DoMenuItem acFormBar, acRecordsMenu, acSaveRecord, , acMenuVer70
End If
End Sub

The function I want to produce is when the button is clicked on, it should open another Form and if a certain field (Sample Name) is left empty, then it will display a message box.

Why doesn't this code work. There's no errors but it doesn't do what I want it to do.

Thanks

Change the syntax slightly,

If IsNull(Sample_Name) Then
Msgbox......

However I would not use the On Focus for the control to trigger the event. Typically you would use the On Click Event or After Update.
lwells