I see that you've fixed the problem, but I had a thought. I hate loose ends and unanswered questions.
Even if your cron server is "the same" server as your web server, you may still need to put in the IP address. If you are running the site from your own computer, then this may not apply.
Large hosting companies (like GoDaddy) have huge systems and frequently, things that seem to be on the same IP are not, or may actually be for some purposes and not for others. I've learned to almost never rely on "localhost" or "127.0.0.1" when setting things up. I try to always call out the server IP address explicitly.
I may be way off track, but I thought I'd stick my two cents in just in case it helps. I spent a lot of time wrestling with GoDaddy's Cron Manager and learned a bit about it.