UIImageView在UIScrollView中不正确。

I've got scrollview in scrollview (one for paging and one for zooming). The outer container only occupies part of the screen. The inner scrollviews are created programatically with frame matching the outer frame but with origin (0, page * width_of_outer). The problem is that when the screen is loaded the inner scrollview doesn't appear at y = 0 but is offset by what seems to be y of the outer frame. As soon as I touch something inside the inner scrollview is moved to correct position occupying the whole outer scrollview. I can't figure why... The frames of inners are correct with y = 0. All are added as subview of outer. Any ideas?I've got scrollview in scrollview (one for pagi