I understand that you are having some issues in order to get your Slingbox PRO with the SlingPlayer for iPad.
The main issue is that the SlingPlayer for iPad does not support the connection with legacy Slingbox models (such as Slingbox PRO, Slingbox AV, Slingbox TUNER and Slingbox Classic).
This application was designed to work with the Slingbox SOLO and the Slingbox PRO-HD, since these models are capable to stream the iPad's higher resolution. On the other hand, the HD Connect cable offers you the option to connect the TV source (cable box or DVR) to your Slingbox using the Component cable. It does not mean that you will get the HD signal on your Slingbox PRO.
In all case, I encourage you to check the general information about the SlingPlayer for iPad through this link.