payment module not working in magento

I have a magento store, and it's payment module is not working. I can add my shipping method, but after submitting shipping method,

it won't proceed to payment mode,

I have enabled cash on delivery. and

I have an amazon payment extension also. When I checked in console, there shows some error, That is client ID is invalid in amazon, But the extension is disabled

, still it causing problem, i think so,

But

Checkout with Multiple Addresses is working without any problem.

Can any one please help me, this is my website link please check

You took the client ID that was given to you by wizard. I ran into the same problem.

1. Go to your Amazon SellerCenter Account.
2. Then from Top right drop-down list select Login with Amazon.
3. From right side select the Application you want the information for.
4. Under Web Settings take the Client ID.