paypal won't accept full auto return url

So according to my zencart I can take american express, mc, visa, discover, and all I want customers to see is another option called paypal to pay with if they choose to do so. My problem is that when I go to put in the website payments preferences (in my paypal profile) it won't except the last 5 characters of the url. The last 2 words are checkout_process and it stops at the pr in process. I've called paypal tech support and both times they said that they knew what I wanted to do but had no idea on how to do it.

Any help would be greatly appreciated!

Thanks!

What is the URL you are trying to use?

I found the solution through a good friend of mine. Turns out he's a dev for frag-ops and fixed the problem creating a subdomain in about 10 minutes. hehe So now people will see 'http://zencart.sandysandersdesigns.com'
instead of some really long url and by doing that it let me input everything paypal wanted in their link, but using the subdomain instead.

Cheers,

and to think all you needed to put in there was
https://www.whatever.com

zen cart sends the correct information in an over ride for each order