Im trying to get Archery training from him, but he won't tlak to me at all. No dialogue box appears or anything. He just says "We're all rich thanks to you. Cheers!" every time I try. I'm the leader of the thieves guild too. Don't have any mods installed or anything like that.

If you have a very high Archery level (i thing 90 and above) - Unfortunately, skills can't be trained beyond that level by masters. !!!

Of course i don't know if that's your case...