Says Ben Smith: 
One of the enduring mysteries of the 2008 campaign was what got Ted Kennedy so mad at Bill Clinton. The former president’s entreaties, at some point, backfired, and the explanation has never quite emerged.
I’ve finally gotten my hands on a copy of Game Change , in which John Heliemann and Mark Halperin report:
[A]s Hillary bungled Caroline, Bill’s handling of Ted was even worse. The day after Iowa, he phoned Kennedy and pressed for an endorsement, making the case for his wife. But Bill then went on, belittling Obama in a manner that deeply offended Kennedy. Recounting the conversation later to a friend, Teddy fumed that Clinton had said, A few years ago, this guy would have been getting us coffee.
The sad part is, Clinton was quite correct., if we’re talking about basing such judgments on Obama’s actual qualifications for the job. But, let’s get real, here and recall who it is we’re talking about…. Think, now… Teddy Kennedy, supposedly being offended by Bill Clinton’s supposedly bad behavior? Yeah, THAT makes sense, right?
I suspect what’s really the story here is that Teddy couldn’t bear to see a strong woman, much less a woman President. Of course, the situation would be reversed were the subject Caroline, for example which should give you an indication of how committed Teddy was to such things.