Old Rotel 965BX won't lock with Marantz HD-DAC1

I have an old Rotel 965BX cd player that I would like to use as a tranport.  It only has coaxial digital output.  When I connect it to the Marantz HD-DAC1 it does not seem to lock.  All I hear is a lot of clicking from the DAC1 and occasion bits of music from the speakers.  I haven't tried to use the DAC1 coax input before.  The other transport I have is connected via optical.  It works fine.  The Rotel line output work fine.

The Rotel is from the early-mid 90's and is mint.  Very seldom used.  My question is, does anyone know if there might be a problem with older CD players with coax output connecting to my DAC1?  Is there something in the locking handshake that the may make older CD players not work with the DAC1?  Or could it be that the Marantz coax input is defective?  I don't have anything else around to try the coax input of the Marantz with.

Thoughs?  Thanks
First question - are you using the right type cable? It must be rated for "digital" - a normal IC may not work.

How long is the cable?

Regards - Steve
I tried several coax cables that I had used in the past with success.  I am only running 3 feet.  So I don't think that is the problem.

Thanks for the response - Peter
The DAC manual states...
- If the sampling frequency cannot be detected, “Unlocked” will be displayed.
- “Unsupported” is displayed when audio signals that are not supported by this unit are input.

Are either of those words displayed on the display of the DAC? 
- Make sure the display is turned on

Coaxial Input states
Linear PCM (2-channel) 32/44.1/48/64/88.2/96/ 176.4/192 kHz
- 16/24 bits

The output from the CD player is - 1 bit

It's looking like there is some incompatibility between the Rotel and the Marantz 

Not perhaps the news you were looking for - sorry
Is the output from the player 1-bit or is the DAC within convert to 1bit?  It may be that the coax output could remain PCM as coming of the disc. Just wondering, don't know myself.