You're not quite clear - do you want yours to be 400V (like your friend's one), or are you telling us that they both don't work?
In the first case, it may not be your fault - it could just be natural variations in transistor gain (no two transistors are exactly the same, unless you buy an ultramatched pair), or maybe your transformer has a slightly different number of turns on it.
If you are suggesting that it should be ALOT higher, then I'm not quite sure - I'll have to think about it a while.