If the SC commands are both working then you probably don't need any files from me (In reference to an email I got a few days ago). However, you can simplify what you're doing with PD/ND. I went through this exact thing about 2-3 months ago. Check out the thread here.
Increment numerical valued variables
I'm not trying to step on Guino's toes. He definitely knows RR's capabilities and the skinning options infinitely better than I do. But using the code I came up with in the above thread you're exectbl.ini will look cleaner, and if it still doesn't work it'll be easier to trouble shoot.
EDIT: Note that in my code, my playlists were actually called 1.m3u, 2.m3u, etc. And I only used 6 of them. You can change the name of the playlist that gets loaded by modifying the LOADLIST command as follows LOADLIST;c:\playlists\playlist$playlistnum$.m3u.
Also, note that my playlists were stored in the c:\playlists folder. You may have to change that path to match your setup, or reference the RR variable which you may have set with RR Config.
You can also change the upper bound by changing the 6 in the ND command to a 12 for your case. If you're really ambitious you can replace the 12 with the variable (plcount) that you added in RR.ini.
Let me know if you have any questions.