Private Sub Worksheet_Change(ByVal Target As Range)
lngcnt = 0
If Not Application.Intersect(Target, Range("G7:G18")) Is Nothing Then
For a = 7 To 18
If Cells(a, 7).Value = "x" Then
lngcnt = lngcnt + 1
End If
Next a
If lngcnt > Range("F2").Value Then
Target.Value = ""
End If
End If
End Sub