AP-45 Midi problem

[jupiter]

I have recently purchased a midi to pc cable, cheap one. I'm using ableton and kontakt as software. There's a signal, BUT when I play more tha 1 note, a chord, there's always a note that stucks sustained in the program. It's very annoying. I changed the cable for another, and the problem persists.

 

Any ideas on this problem? 

 

Thanks