Usernames in Sudoers have #

We have users that have a # in their username. Sudo is working on some servers and not others. I have narrowed it down to the # in their username. Any suggestions or ideas why it is working on 1 server but not another.

Server not working is - Solaris 10 patch level 138888-01
Server working is - Solaris 10 patch level 137111-01

Figured it out just need to add a \ before the #