No worries, I am glad my blog entries have helped. 12 Meters shouldn't require the increased voltage setting, normally you only need that after about 50 meters or so, unless you have cheap connectors or poor quality wire, or perhaps it's because of the dual throat LNB from Sky, I have about 35 meters from DM to LNB, and it's cheap cable, and have never had a problem. It could be a dodgy power supply, but I am glad it's working now.
I also forgot to mention that I also have a dual throat and Moteck motor, so perhaps it could be a dodgy clone, or a dodgy power supply. Are the F Connectors in line with the RS232 serial port connector, or the RCA Audio/Composite connectors, if they are in line with the RS232 then it's a bad DM, if they are in line with the RCA then it should be ok.