That's right because in MB64e the pots are treated as a type of encoder. See here for more info Anyhow, mind if I ask what app you used to view the sysex? The output appears OK to me, but this hex viewer is not the best thing in the world to read with. Still, I see the whole file as it seems that it should be... So once again I have to ask you to post more information. I stil need the ini file. As well as that, would be good if I could get the output of the script in debug mode, with both the original file and the customised file... so: perl mk_syx.pl midibox64.ini -debug > midibox64.txt perl mk_syx.pl pesce.ini -debug > pesce.txt Then attach pesce.txt, midibox64.txt, pesce.ini and pesce.syx to your post.