Global or not, a conditional value list can be set up to work. The conditional value list is controlled by a value in a second field, so the fact that your conditional value list is used as the formatting for a global field makes no difference here.
i have it working, but took off the global field because it wasnt needed as a global as i needed unique values per record. I took it off and it doesnt seem to have affected my script with the layouts which is great.
many Thanks for the reply