You must set the receiver to the proper mode, then you enter the code.
Home>Home>Settings>Remote Control> Scroll down to Volume and Mute buttons and set it to control Auxillary Devices' Volume (hilite the line and pressing select on the remote toggles the receiver between TV Volume and Auxillary device volume).
Since you have a 54.0 remote it should have a database in it for your device, if not you may need to have the remote "learn" the code from your HT remote.