GUI Button hover not run on android!

Hi every body! I have one problem with unity gui! I create main menu with gui button. And create my GUI skin for button. On window, it run ok with normal, hover, focus background. But when i build on android, it run only normal and don't change hover or focus background when i touch! But when I remove GUI skin. I saw default effect of gui button when touch in it! So how do I create my effect with hover and focus on gui button on android?

Thank you very much!