Snapchat friend request issue

Hello! Here's my problem: a while ago, a friend removed me from his Snapchat friends. (I assume, because I can no longer see his score but he still appears in my friends list).
Today, he wants to re-add me to his friends, but when I give him my username, he says it doesn't work, that he can't click on add.
I've already tried to add him myself, but it doesn't seem to work either (he doesn't receive my request).
Help us out!