Yes.. we're talking about an older version of Sling Media's Stand Alone Sling Player application for windows.
Because the stand alone application was never designed with the command structure needed to operate the DVR functions (this case "dvr" button twice, arrow up/down and select to open a recorded dvr event, "play" starts said selected DVR'd event) it doesn't have a command set that works across the Sling *Adapter*.
Sling Boxes (stand alone & externally connected box) have an IR blaster feature ... which sends IR signals outward as if they were your remote control. These IR commands would then activate the additional features of a Dish Receiver ... or if you've a pro slingbox with multiple connections, you program in, for your Dish Receiver, a Bluray, and maybe a DVD player.. so... the commands get sent through the box to the IR Blaster ... read by the receiving box, and take the appropriate action..
As you have a working Sling Adapter ... glad to hear it.. I do too ... but others don't.. also.. have you tried access Dish Online .. while at your TV1 location.. and tried playing any DVR event ... to see if it also starts playing ton TV1?