back wheel wobles after 44T sproket is put on.

bearings have come out? thats what happened to me. is everything done up properly ?

if your rim was already slightly buckled,putting the sprocket on there doesn't really help.
a lot of the new style rims are very cheap especially the spokes.i used an old rim that
was rusted, off a repco bike and it is very strong.if you can get an older wheel i think there better
but if not then a new one. they can be pretty expensive and you get no warranty because
of what we do. bolt it in a star pattern when you tighten the sprocktet and try to tightn
it evenly and leave it. the new rims will bend the spokes,personally i reccomend getting a
good non buckled rim off an older bike with stronger spokes and using that.
as far as i am concerned, once a rim is buckled,its stuffed.

If its only wobbling a little bit, it just might need 'truing'. A local bike shop can hook you up, or you can try it yourself. You'll need a spoke tool though, usually $5 max.

Check out this article:
Truing Wheels

I'm assuming you put it on to tight, and slightly bent the spokes. I did this before.