Private Sub lstValues_Change()
Dim iCounter As Integer, iCount As Integer
For iCounter = 0 To lstValues.ListCount - 1
If lstValues.Selected(iCounter) Then
iCount = iCount + 1
End If
Next iCounter
If iCount = 3 Then
cmdOK.Enabled = True
Else
cmdOK.Enabled = False
End If
End Sub