3 answers

A few things - some are obvious, some are not - just trying to cover all of the bases:1) Do you have your endpoint in Remote Site Settings?2) Can you set the endpoint in the WFR OB to a service such as http://requestb.in/? When integrating with custom endpoints (presuming behind a firewall) a lot of things can throw a wrench in the works. This way you can determine if it's salesforce.com or your custom web service that's the culprit.3) Odds are you won't see much in the Queue - it goes so fast I rarely see anything I'm sending. =)