Help with Authorize.net

Hey all,

So I'm working with a shared linux host on GoDaddy.com and trying to integrate an Authorize.net account. I've been able to successfully process transactions via osCommerce, but want to create just a simple payment form and can't seem to do so. I've tried both the PHP SIM and AIM sample code from AuthNet and haven't had luck with either. I plug in my transaction key and login ID to both but they either error or just don't seem to come up right.

I've also scoured hotscripts.com for a script that would help and haven't found anything there either.

Is there a common issue with GoDaddy and AuthNet?

Any help is very much appreciated. Thanks.