Is the code embedded in the document itself or does it reside in the attached template or does it reside in your own Normal.dot?

If the macro is not in the document then do the other users have access to the same template filepath?

If the other users have disabled macros (this is on by default) then your macro won't run unless the document (or template) which houses the macro is stored in a 'trusted location'.

As you can see, using a macro is not pure and simple when lots of people are going to be using the file.