World of Warcraft Recruit a friend problems?

OK so i did recruit a friend with a friend. I am the veteran account. I made a druid and he made a warlock we were getting 3x xp fine at level 20. I decided to make a death knight so i could power level him. When we tried to get him xp it was only 1x. My death knight is 58 and hes 24. Why isn't this working?