A couple of things to look at/check:
Are there three green LEDs on the external DECA?
Do you have any errors when you run a system test on the HR24?
On the HR24, you can run [a more detailed] coax network testings from the front panel.
Press guide and the right arrow [both] and [it may take more than once to get it] you'll see a screen with coax to the left. Select it and the first test will show all the DECA nodes, and the loss to each. Then select Phy Mesh and this test will show the quality of the signal between each node.
Are there three green LEDs on the external DECA?
Do you have any errors when you run a system test on the HR24?
On the HR24, you can run [a more detailed] coax network testings from the front panel.
Press guide and the right arrow [both] and [it may take more than once to get it] you'll see a screen with coax to the left. Select it and the first test will show all the DECA nodes, and the loss to each. Then select Phy Mesh and this test will show the quality of the signal between each node.