Make sure ye use a fork bung, not a star nut (M:Part ones seem to have a good rep), and that it's at the right depth to take the compression of the stem.
See if ye can find some of the fitting paste stuff (I use the stuff that came with an fsa seatpost- kind of a gritty gel, provides friction, I suppose).
It's always worth lookin' on the manufacturer's website, if ye know it, to see if they've any installation instructions as pdf's.- such as:
http://www.eastonbike.com/TECHNICAL/tec ... nstal.html
Used this for a set of easton forks I got.
_________________Yer Power b'roight Weak, Old Maan- Oi'll tek yon Loightzaber an' Stick it Up Thy Bum!
If only they had let Dave Prowse do the voice.......
...............buy my old tat!!