I'm with Dave here. I have the v572a and it can pick up signals all the way down my driveway (270 feet). I actually did a test with it and carried a motion sensor walking down the street and it still picked it up.
If you have someone to help you, one of you can watch the led on the v572a and the other walk in front of the sensor. If the led comes on then you know the signal is being received.
If the signal is being received I would imagine the v572a is not the problem, unless it's not putting the signal on the powerline. A good way to test this would be putting a lamp module or appliance module on the same outlet as the v572a and see if it will turn on.
Next, if you don't have a phase coupler you might want to make sure that the cm15 and the v572 are on the same power phase. If it isn't try put it on the same phase and test again. If it now works then leave it there, or if you can't leave it there then probably a good phase coupler, amplifier, repeater would be a good investment. (XTB-II).
Also if you are using the v572 you should go into AHP and set transceived codes to none. (this is how I have mine setup and works very well)
Hope some of this helps you out.