Ultimate SEO breaks Buy Now buttons

[AddVant]

We have the BuyNow option on for product listing.
it works fine for the category and other search results but when we are on specific Manufacture list then the new page that open after press the Buy Now is blank.
We see a deference in the button link:
on regular it show:
http://www.addvant.com/ip-phones-c-6...y_now&sort=20a
on the Manufacturer list it show:
http://www.addvant.com/index?product...facturers_id=9
we use 1.3.7.1 and Ultimate SEO

When we either change the index? to index.php? or the page name before pressing the Buy Now - it works fine.

Please help.

[Ajeh]

What happens if you turn off the SEO ... does it start working normally?

[AddVant]

What happens if you turn off the SEO ... does it start working normally?

Yes, When turn off the SEO it works as it should.
Thanks for the prompt reply.

[AddVant]

Yes, When turn off the SEO it works as it should.
Thanks for the prompt reply.

can it be resolved?

[Ajeh]

Fix the SEO code?

[AddVant]

Either the SEO or the add to cart - which you think is the one needed to be Fixed?
Thanks

[Ajeh]

Zen Cart works ...

Add SEO it breaks ...

Fix the SEO or don't use it ...