I don't have any problem with the Luken MUX at all. Last evening I checked the signal level on SES-2 and it was 95/90. It would be helpful to know what you're not getting verses what you are getting. I have had times when the signal level would drop to zero and a second later come back on while you were watching something.
Look to see if the transponder VoomVoom listed is in your transponder list. If not, add it using that information, save it and then do a blind scan on that one transponder. No need to do a full scan. They should scan in and work fine.