presentModalViewController desnt animate on iOS < 4.0

Question

[self presentModalViewController:navController animated:YES]; 

I have scroll view with page control and paging enabled, each page has buttons who when pressed present modal view controller with additional data.

when running on device with iOS 3.0->3.2 modal view controller on first page of scroll view animates properly (view scrolls from bottom), but rest of them just turns scroll view black for part of a second and pops view instantly...

On iOS 4.0 and greater everything - all animations, works as expected..

Would apreciate any kind of help, and trying to find out if anyone tried anything similar and bumped into same problem...

Thanks in advance...