I am in a single-user scenario, and I have the API Key and Token added to my solution, but the solution returns a "Credentials are Missing" message when I attempt to hit any of the service functions.
When I use identical Key and Token in the Tester/Debugger page calls work without issue.
__ccUserServiceContext = new UserServiceContext(__ccAccessToken, __ccApiKey);
ConstantContactFactory serviceFactory = new ConstantContactFactory(__ccUserServiceContext);
__ccListService = (ListService)serviceFactory.CreateListService();
__allCCLists = __ccListService.GetLists(null);
From what you've provided, it should be working. As a quick test I pulled your sample code into a very basic console application and was able to successfully get the lists from Constant Contact. Is it possible to provide a bit more detail on the exception/error message? You would want to strip out any sensitive details such as the API key or Access Token, but it would help to be able to see more specific details.
Alternatively, you can also contact us via email with the exact details of the error so that we can look deeper. For that you would email us at firstname.lastname@example.org
I just sent a sample solution and more information to the webservices email.
It looks like it very well might be a network related issue - just need to narrow down what needs changed on my side.
Here's an update for anyone seeing similar issues. In this case the problem was related to a proxy and traffic not being properly routed through the proxy. If anyone has questions, please feel free to create a new topic or reply here if appropriate!