Thanks for using our answers forum here! I'm sorry that you're having this issue, however the Slingbox PRO is not a model we support for use with SlingPlayer for iPhone. I do apologize about any inconvenience here.
Here is an article form our support site regarding compatibility, Slingbox models and SlingPlayer for Mobile Devices etc:
Furthermore, if you are interested in upgrading your Slingbox you can do so with your current unit's serial number right at Slingbox.com/upgrade.
Hope this helps!
The Sling Moderation Team