Friends and Foes Problem!

I got a message from a user on my forum saying that she tried to add another user to her friends list, but it said "This user does not exist" so I went and tried and it didn't work for me either. I went to her profile, copied her username, pasted it in the add bar and pressed add, but still nothing!
help please!
thanks

Have you tried to visit the other persons profile and clicking on the "add to friends/foes list" link directly instead of pasting the name into the add-user bar?

that was the first thing I did!
then I had to re-try it