2CO won't work with Membership plugin-'There was a problem connecting to 2CO. Please try a

I am using Business Portfolio child with WordPress 3.0.4 and BuddyPress.

I cannot get my new 2CO account to work with the membership subscribe function. I have set up the subscriptions, have added the products to the 2CO site (I can generate buttons and HTML code, but I want it to work when someone subscribes–if I am supposed to put that code somewhere I sure don’t know where). I have activated the gateway and made it public.

I have looked through all of the forums and done everything advised to solve this problem. I have downloaded and installed a new php file as suggested in one forum answer. (Attachments .[zip] gateway.twocheckout.php.zip (3.8 KB, 1 downloads) 11 hours old ).

I have added a new API user and put that in the 2CO settings on my site. Whenever I test the subscribe function I get a notice next to the item—There was a problem connecting to 2CO. Please try again. I have attached a screen shot.

Please advise. Thanks.