Cable Test Light sequence

Hi, I am testing an RJ12 cable. It is used to download our in/out clock data to the computer. The connection is from the main clock, we have an RJ 12 cable to a DB9M. It’s not downloading the data, so I am trying to figure out what is wrong. I tested the other cables CAT5 and it is all good. Now I tested the RJ12 cable and 3&6 -> 4&5 lit up. I am not sure if 1&2 is supposed to light up too…
Please help