Sometimes we hear from customers that they are not getting a signal from the Direct/Line/Sig Out of their amp. The immediate assumption is that there is something wrong with the output specifically. But it is very rare that this is the case.
If you are attempting to run this output of your amp and are not getting a signal, make sure you check for the followings things:
1) CHECK YOUR CABLE: We know, you hear it all the time. But make sure you check anyway. Try running it with a different, known working cable to see if it alleviates the issue
2) DOUBLE CHECK THAT YOU ARE RUNNING INTO MIC INPUT: If you are running into a PA or mixer, you will need to make sure you are running the amp's signal into a mic input. The amp's direct/line output is a mic output as it's essentially a replacement for putting a mic in front of your amp. Plugging the amp into an instrument input will result in no signal being produced.
If you are getting a signal, but it is a bit weak, then this article will be of assistance.