Organ musicmxl and Staffpad

I have been using musescore for some time and have been using staffpad on windows for smoother playback with its libraries by importing .xml files . Unfortunately there is a large amount of lag and stuttering on musescore using spitfire audio libraries. This works extremely well on Staffpad with orchestral files . However, I had imported an organ piece from musescore into Staffpad and it didn't recognize the file and an error message was" only single and double staved parts supported ".It doesn't seem to recognize this at all. Oddly I put the same music into scanscore and imported this to staffpad with no problems. I cannot find a solution for this anywhere.