Prevent macros running after message box show

Hi, herukuncahyono,

tell VBA to exit the sub?

Sub RunMe()
Dim icell As Integer

For icell = 1 To 4
    If Range("A" & icell).Value = "" And Range("B" & icell).Value <> "" Then
        MsgBox ("There is an error in Row " & icell)
        Exit Sub
    ElseIf Range("B" & icell).Value = "" And Range("A" & icell).Value <> "" Then
        MsgBox ("There is an error in Row " & icell)
        Exit Sub
    End If
Next icell

Range("A1:B1").Value = vbNullString
End Sub

Ciao,
Holger