Michelle,
Can you describe the URL you mean? Like the short bit.ly URLs? or yourdomain.com/short-name ?
The problem may be in the resolver because bit.ly/JDHDS?mkt-tracking token is not going to be recognized by bit.ly and will fail somehow, at least that's what I think would happen.
To get around that, just put
mktNoTrack
in the Class of the URL dialog when you create it in your email.