What I understand from your post, is that you can't connect from a remote location.
In this case, what I would recommend, is to make sure that the Internet Viewing is properly configured from the Slingbox location, besides discard any streaming restriction or dynamic IP address from your home network ISP.
You can also check the following link which will provide information about the Internet Viewing feature.
Have your set it to use a internal lan "Static IP" in both your router and from the option to do so on the slingbox? If not, your problem might be thst your router is giving it a different ip which may confuse any port forwarding rule you have made for remote viewing.
I'd start looking there first to solve your issue.