Youtube cutting away last seconds in alot of my uploaded videos

[Kloppstock]

I dont know if this problem is caused by Youtube or Sony Vegas 7

have created a 2.28 min long wmv movie in Vegas, and rendering it

But when uploading to Youtube something cutts away (exclude) the last 3 sec of the video, which accually contains the master joke here lol

Its not the first time this happend with Youtube uploads, but not allways, allso happend when still used Win movie maker

but have generally only been 1 sec early cutt there, so it could be accepted

Either i must fill out the Vegas project with +5 sec black picture, that youtube can eat up, and re-render (+ 2 sec didnt to any difference in any case)

or i must choose different codec settings and such in Vegas before doing that, or i must simply change some unknown settings in my youtube channel?

Have consulted Vegas manual, but i find it really hard to know which area i could find info about this lol,

anyone else familiar with this syndrome?