The issue you are dealing with is that you have the DishNetwork 622 dual tuner box. If you cannot control the Slingbox, this means that you will need to check the connections on the back of your satellite receiver.
Since you have a dual tuner box, you must connect the Slingbox to the TV option designed for IR (Infra Red) signal. The other TV option (RF) is the one that must be connected to the TV set.
Once you make these adjustments, you will be able to control your Slingbox without affecting to home viewers.