books won't download to kindle/amazon app since upgrading to IOS5

Ever since I upgraded my IPAD 2 to I0S5 I can't download books to my kindle/amazon app.
What do i need to do to get the books to download and open?

I have tried deleting the kindle icon and reinstalling it.
I tried deleting all the books and redownloading.
Whenever I try to open, it gives me an error message and to reinstall.

Is it because I need an Icloud acccount?

 

I had problems when the new Kindle app rolled out. What I had to do was make sure I was on the cloud tab, then pull the blank screen down to sync with the device with the cloud. That's when the books showed up on my display.

 

I was having the same issue and then I realized I wasn't pulling down on the screen to sync it. I was just sitting there waiting for it to download automatically like my real kindle does.