jquery - jQuery UI sortable and scrolling together are not working

Question

I'm using jQuery UI sortable in a jQuery mobile app. Without window scroll my sortable items work and stay in the containment. But if I scroll the window and start sorting the items, my items move first to the same height of my window scroll and then no longer stick to my mouse pointer! What did I do wrong?

Here is code which I have been trying:

$("#ulList").sortable(
{
    axis: "y",
    containment:"parent",
    disabled: false,
    scroll: true,
    scrollSensitivity: 100,
    scrollSpeed: 20,
    cursorAt: { top: 5 }
});

One thing I know is that scrollTop is not going to work here as it's jQuery mobile, but I need something to replace it.