djuced will not load demos or tracks

my son has a dj control air plus. on our laptop with windows 10 it works fine with the 3.6.9 version. now he has gotten a desktop and we downloaded djuced. first newer version, afterwards the same version....every time it gives the same problem; it will not load demos or tracks. we can browse, but when we select it and press load a or load b, in the bottom  on the left, right next to where it says ready, it says, only very short, that the file exentsion is not supported (all in dutch, since we live in holland). i tried with the laptop again and that works fine. now again on the desktop, but it still does not work. the loops with sound effects do work...anyone have any idea on what it wrong?