I have been struggling with fixed positioning in iPad for a while. I know iScroll and it does not always seem to work (even in their demo). I also know that Sencha has a fix
The simple way to fix this problem just types transform property for your element. and it will be fixed. Happy Coding :-)
.classname{ position: fixed; transform: translate3d(0,0,0); }
Also you can try his way as well this is also work fine.
.classname{ position: -webkit-sticky; }