Bad example. The Lisbon treaty was voted down by the Irish in the first referendum. But then the EU made changes in the controversial areas and then the Irish were asked again. And they were happy with the changes and as such with the 2.0 of the treaty.
They had a second referendum? France wasn't so lucky. Our government in its unfathomable wisdom foresaw that the people wouldn't listen to reason if they were entrusted with this decision a second time (we voted no the first time, by a wide margin). So they did the smart thing, and asked the parliament instead. The result was as predictable as it was different.
So yeah, changes. Not just what, though. Who. You gotta ask the right person to have the right answer, democracy be dammed.
(Just to be clear, I will resent them for a long time for this. Representatives should not be able to override the people's direct decisions.)