Editor line counter !

[vbNeo]

I am making an HTML editor, and i'm in the progress of making a counter in the left side of that screen, that shows wich line youre on, like i other editors as editplus... I use sendmessage, but i cant get it too work probably, here's the code i'm using:

Private Sub Form_Load()
Counter = 1
List1.AddItem Counter
End Sub
' Note "Counter" IS declared in the declarations !
Private Sub RTB1_Change()
Dim LineCount As Long
LineCount = SendMessage(RTB1.hwnd, EM_GETLINECOUNT, ByVal 0&, ByVal 0&)
' Add line
If LineCount > PrevCount Then
Counter = Counter + 1
List1.AddItem Counter
End If
' Delete Line
If LineCount < PrevCount Then
Counter = Counter - 1
List1.RemoveItem Counter
End If
End Sub

My problem is that if the user deletes more than one line, the listbox only get's one number removed .
This is driving me nuts !

Please help !!!

Thanks in advance !