subscript out of Range (Run time error 9), need help

Hi,

AM having an error "subscript out of Range (Run time error 9)" in this macro

Sub ss()
FileToOpen = Application.GetOpenFilename _
(Title:="Please Choose the RTCM File", _
FileFilter:="Excel Files *.xls (*.xls),")

If FileToOpen = False Then
    MsgBox "No file specified.", vbExclamation, "Duh!!!" ' Notification that nothing is chosen
    Exit Sub
Else ' Load the file, copy the first sheet and paste it in active sheet ...
    ThisWorkbook.Activate
    ThisWorkbook.ActiveSheet.Range("A1:Z65536").ClearContents
    Workbooks(FileToOpen).Activate
    lrow = Workbooks(FileToOpen).Sheets("Sheet1").Cells(65536, 1).End(xlUp).Row
    Workbooks(FileToOpen).Sheets("Sheet1").Range("A1:Z" & lrow).Copy
    ThisWorkbook.Activate
    ThisWorkbook.ActiveSheet.Range("A1").PasteSpecial xlPasteValues
End If
End Sub

I highlighted a line, where i get this error.

Please help

Thanks