In most areas chorus are only transmitting from 218.000mzh up to 378.000mzh.I know you need higher frequencies if you are receiving your signal from one of these screw type aerials which are on the net.If you have one of these aerials try doing manual scan at 618.000mzh and at 8.000mzh intervals after that.
Ch0rus are piping MMDS signal through cable in some town on the higher frequencies and also sending it out by aerial to the surrounding areas, using the higher frequencies.
The higher frequencies will work if they are applicable to you ie, if there is a signal to be picked up in your area.If you know 1 frequency in the higher range do a manual scan on that frequency with network scan enabled and you should pull in any channels in that range.