Facebook Issue

[saintpeter48]

I have problem with Facebook.
I have started a Facebook page for a quiz that I run, i've added lots of members without a hitch over many months but I had a problem with a friend that wants to join the group but his request just doesn't register, he has requested to join and I have invited him to join, but an error message keeps appearing, saying, 'problem, try again later'.
Any ideas what is wrong?