2 player popn mode crash

Hello.
I'm making a theme + noteskin to play with stepmania in popn mode.
In 1 player mode theres is no major bug, it's playing.

But anytime i try to launch popn mode with 2 players i get a crash with the error : "No compatible styles for popn - pnm-nine with 2 players" or "No compatible styles for popn - pnm-five with 2 players"
So is it theme related or is it that stepmania popn 2 players mode doesn't exist at all ?

Thanks

Stepmania does not currently support two players in popn mode. The source code would have to be modified to add support.

Thank for the answer (too bad i'm not able to do it myself T_T)