Need help!xfile with skinned mesh export from 3ds max doesn't work!

I download some .max role model with bones.And I create some animation in 3ds max and export it with panda plugin.But it cause my program crash.But some of these model works fine.
Then I create an model with skinned animation myself and export it!But some vetex position got wrong and the animation is different from what I made.
So is there some action must be done before I exporting models to x in 3ds max?
Or is there articles about how to write an own format and 3ds max export plugin?

Any help will be appreciated!Thanks!