Apps wont download to my ipad2

I used itunes to download apps on my imac but after the app has done download， i plug in my ipad， it said its syncing， how ever when i check my ipad，the icon was there but its waiting to download. Why is that？ thank you very much for help this is my first week with my pad pad.

Try this:

Hold the power button and the home button down at the same time until you see the Apple logo.

Let it reboot ~

Let us know!