admin_usergroup_edit doesn't seem to be working

[Wakey]

I have thrown together a modification for a client where when a user is promoted using the promotion critera it sends them a private message informing them. As each usergroup has unique benefits each message needed to be unique so I needed to add a new field on the usergroup edit page to store and change each usergroups PM message.

I did this using the admin_usergroup_edit hook and it worked fine on my local test server but when implementing the modification on the clients server the field to enter the data refuses to display. I have installed it on 8 other forums running on a variety of hosting solutions to test and it works fine on all of them so it doesn't seem to be a code issue.


It have been trying things all day to isolate the problem and resolve it but with no luck. Has anyone encountered this kind of issue before or have any ideas of what may be causing it?

The code I'm using is below but I'm failry sure that isnt the problem

PHP Code:

print_table_header('User Promotion Notification PM Message');  
print_textarea_row('Message to send on promotion to this group', 'usergroup[pm_promotion]', $usergroup['pm_promotion']); 
print_table_break();  
print_column_style_code(array('width: 70%', 'width: 30%'));