I\'ve read a few of the other posts on getting started with implementing Facebook credits and I\'ve downloaded the sample code from github: https://github.com/facebook/credi
I found out what the problems were:
In order to get this to work, you need to have the company registration filled out.
After that is done (and this was not obvious), you need to actually select the company from the drop down list. This is all done in the credits section.
You must have a secure canvas url set in the basic settings section (i.e. https://example.com/app/index.html)
I'm not sure if you have to have the callback as a secure url in order for the test to work, but it does make sense that this would be required.
The test will not work in sandbox mode.
Hopefully this will help others that may run into similar problems.
Now I have to figure out how to get this to work using the facebook-actionscript sdk.