I followed the installation instructions on how to install the subwoofer, using the front left and right speaker wire terminals on my receiver instead of the subwoofer cable, and I have not been able to get any sound at all from my sub. I then tried hooking it up using the sub cable and still no sound at all. Am I doing something wrong? I followed all the instructions but I think I might be missing something down the line somewhere. Can someone please help? Thanks in advance.