I have a coolsat 4000 pro, sg2100, fortec 80cm dish. I can get all the other tp (11.800, 11.987, 12.116, 11.807). These all come in with signal b/w 70 - 82 and quality of 65 - 75. But whenever I try any channel on 11.720, it is constant freezing and broken audio, but the signal is 79 and...