Excel Timestamps (Not Working When Workbook Is Protected)

Hi;

I have a small problem with this time stamp I am using.

When the worksheet is not protected the time stamp I am using works fine and enter's the time correctly as I want it to. Though when I lock the cells in column 3 and enter data into column 2, I am getting this error message.

As you can see the first time it worked (when it wasn't protected), and the second time I locked column 3 and protected the worksheet and it did not work.

http://s30.postimg.org/rlt1aquqp/Error.jpg

This is the only code I am using as well;

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 2 Then
Cells(Target.Row, 3).Value = Time
End If
End Sub

Any help would be greatly appreciated.

Regards;

Andy