Over flow Error

Dear All,
I am using this code to get the Line Number from a given position in a Richtextbox.

VB Code:

Option Explicit
Public Declare Function SendMessage Lib _
    "user32" Alias "SendMessageA" _
    (ByVal hwnd As Long, _
     ByVal wMsg As Long, _
     ByVal wParam As Long, _
     lParam As Any) As Long
Public Const EM_LINEFROMCHAR = &HC9
Public Function TextBoxLineNumberFromCursor(TBox As RichTextBox, pos As Long) As Long
 
  TextBoxLineNumberFromCursor = SendMessage(TBox.hwnd, EM_LINEFROMCHAR, pos, 0&)
End Function
 
'and  I call this Function as 
Dim x as long
'rtb is richtextbox
x=TextBoxLineNumberFromCursor(rtb,32271)
 
'and I am getting an oveflow error for this
'I dont know why