Thank you for using our online forums. I'm sorry to hear that you are having this issue with the Slingbox PRO. I first would like to know if you had someone in the Slingbox location try and connect? In the mean time you may also want to check out the firewall settings on the router that the Slingbox is connected to. You may need to port forward the Slingbox on your router.
Here are some links to articles that may help you.
Hope this helps
Sling Media Moderation Team