Venue 7130 Pro/7139 Pro dock not seeing external monitor

Dell_Tablet_Dock_Update_Tool_WJGFG_A05_ZPE's ST4320AUX.exe app reports "Error: Tablet cannot detect external monitor through Dell Desktop Dock":

The TV / cable setup works great through the Venue Pro 11 internal HDMI connector.  I simply pulled off the mini adapter and plugged the HDMI cable into the dock.

The dock works as a) it is charging the tablet's battery and b) I'm using a mouse and keyboard plugged into the back of the dock.

The Samsung TV recognizes an HDMI cable is plugged in.  Select source on the TV shows the HDMI port grayed out until I plug in the cable into the dock.

BTW: I purchased a DisplayPort to HDMI cable.  The dock's DisplayPort behaves identically to the dock's HDMI port.

Questions:

• Is there some type of utility that shows me what might be going wrong with the dock? 
• Or, is there a connection that drives the video that could be bad or dirty?
• Is this the latest dock firmware?  (It was a bear to find!)

I just ran the latest auto-update update including:

• BIOS update 7139_A21.exe
• Intel HD Graphics 4200 driver version 20.19.15.4531