I added a line and am very sure there is no indentation problem. Here is the error report and screenshots of the text so you can see it:
Error: File "C:\Users\info\Desktop\Claas UI.blend\Claas_UI_2.py", line 40 bpy.ops.object.mode_set( mode = 'EDIT' )
TabError: inconsistent use of tabs and spaces in indentation location: :-1
Error: Python script fail, look in the console for now...
When I remove the line with the arrows and uncoment the previous lines below it all runs fine.
Any idea what causes this?