First, did you clean the inside of your shafts and the inserts before installing? If so, what did you use? I use acetone for a cleaner--works great.
I've had great luck with 2-ton epoxy for gluing in the inserts. I've also used the short, fat hot-melt glue stick from Kustom King, and so far so good, but not enough shots on those to draw any real conclusions. It does work excellent with wooden shafts, but the jury is still out with carbon.
Chad