New Remote RC66RX not working with HD DVR - DirecTV

I have recently received a new universal remote control RC66RX as a replacement for my existing RC65RX one since a number of buttons stopped working on it. The new remote does not communicate at all with the HD DVR HR24-200.
I am not sure if it's because my old remote is still in range.
No matter what button i push on the new remote (batteries are in place and have been checked with another pair to make sure is not that), the HD DVR does not respond to it. The light on the remote flashes when i push any button.

Thank you

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