Hi Nimtrix
Thanks for your help. I tried the anglediff expression making it equal to or less than 0.5 and it worked. I'm so pleased as I have been trying to fix this for a while.
By the way, do you know why the 'within 0.5 degrees' condition didn't work. I would be useful to know so I can learn from it. It seem to make sense logically and therefore made it hard for me to see why it didn't work.
unplugged