No more AMC with a Pace DC50X Digital Transport Adapter

Lost AMC in the conversion to digital with a Pace DC50X Digital Transport Adapter from Comcast. With the conversion of a block of cable channels (39-60) to digital, I thought I was prepared with a Digital Transport Adapter (DTA) box and a Motorola set-top box provided by Comcast. The set-top box works fine (so far), but with the DTA can't get A&E, AMC, USA, FX, and a few other channels. Calls and emails to Comcast support aren't helpful. I keep getting told that those channels are unavailable for DTA's but when I ask for a list of all channels viewable with a DTA they send me a list including precisely those very channels. Can anyone from the Oakland CA area with the extended basic (now digital starter) plan get those channels with their DTA boxes? Having been able to watch any cable channel within my plan in any tv in the house, it is frustrating that I am now limited to where the Motorola box is connected for certain channels.