Hi oldcastlewflorida,
I appreciate the time and effort that you took to troubleshoot the issue. I understand it could be troublesome to isolate the point of failure sometimes.
As the Monitors works fine when connected directly, so we have confirmed its not an issue with the Monitor. Now, I would suggest to check with different cable before replacing the dock.
If you have any further queries, please feel free to contact us.
Thanks and Regards
Sandeep P
#iworkfordell