are you sure that you have the ir routed properly?  you don't have the mr slim assigned to the "front" on the nc50 by chance?   the mr slim should not be assinged to anything on the nc50, then the commands will be sent via the ir blaster on the remote itself.   

use a  camera to verify that ir is coming out of the remote when a mr slim button is pressed.  a camera phone works fine for this purpose.  

if you have it routed properly and ir is coming out of the remote, then email me a file with the codes you have learned.  i can teach them to my pronto and convert them to hex and see if anything looks funny.