Ok so, here's the story. I've avoided EXP parties for the longest time, mostly ever in fact. I decided to try one today as a R37 WHM. We go somewhere with lots of ra[ptors, I want to say it was Broken Water or somesuch. After about 45 minutes of things, a few party members break off from our main group, try to solo a few raptors and die. I don't get why this happened, but after it did happen I basically got the 'you suck at WHM' indication from them. I'm wholly willing to accept that it was my first go and I'm not perfect but could I have been that bad if:

Constantly casted regen on the tank.
SP Cura/Stoneskin and sometimes Regen when it was necessary.
Kept my MP in check.

The only thing I didn't do a lot of was cast offensive magic, though I did throw a stone sometimes but other then that, this is all I did, and we had few deaths. Am I missing something here? Any tips or pointers would be appreciated, but I really think I did ok enough. :|