Magento - Check Out, over and over again?

Hello guys

I have tried many times “Placing Order” but it return to “Check Out” page again and again.

When i check out as Guest.

How do i fix this? any advice please.

Below is the link of my magento testing page.

Thanks in advance.

You didn’t mention some important details : is this YOUR script for placing orders? Are you using PayPal ipn for processing orders? Can you post your code here?