problem about altlvds PIN assignment!

Since the pin-location matters, I assume you're doing a timing simulation instead of a functional? (I'm not a big fan of timing sims, but that's another post altogether). So what's probably changes is the timing.

Now, the altlvds is Hard IP, so I doubt it's timing values have changed, but going into the core it may have. When you say you don't get correct results, what does that mean? Are bits not aligned or are you getting incorrect data or Xs or a hard error?