Paypal Url Problem

[brd]

Hi,

 

I have a problem with my shop.

 

I have installed the default paypal module and configurated it.

 

But i have a problem, when i proceed to my order checkout and i choose the Paypal payment i have a 404 Not found page because the url called is wrong.

 

The normal url of my shop is : http://shop.mydomain.com

But Paypal call : http://mydomain.com/modules/paypal/express_checkout/submit.php

 

 

Can someone help me please?

 

Thanks.