DVR Chatter

Hi.  I have Comcast digital cable service and my set-top box is a Motorola DST 3412 DVR.  I've had this box for several years.  During that time I have used the box's component video out along with analog stereo out.  It has worked fine and the set-top volume control has been used via the Comcast remote control.

A couple of days ago I decided to used the digital audio so that I could hear the audio in surround sound so I removed the analog audio cables and replaced them with a digital audio cable.  It did produce a better sound quality and programs that were being broadcast with Dolby 5.1 were automatically detected and played in the Dolby format.

However -- Seems like there's always a "however" doesn't it? -- the remote control no longer controls volume.  The little volume scale is displayed at the top of the TV screen and the bars indicating volume level will increas or decrease but there is no discernible difference in actual volume.

If I had an optical cable I would try it to see if the problem is the same for that output but I don't have one.

My question is "Should the remote automatically control the digital audio outputs or do I need to make a change somewhere in the box or the remote itself?

Thanks in advance,

Howard