Onepage success page source

I’m trying to add some google tracking scripts to onepage success.

But I’m facing a problem in this page.. the url is :

checkout/onepage/success/

but when I click on view page source in my browser it’s redirect me to another page :

checkout/cart/

Could you please help ? how I can stop this redirect ?

Please note that I’m using custom theme.

Looking forward for your quick assistance.