Line out to Octatrack

I know this is a stupid question, but I am going to ask it ...

I have MPC studio x working in logic pro

I want to get this sound out via the octatrack into my new RC 505 MKII

However, I plug audio out from MPC and into Octatrack... nothing... but my octatrack is fine as i have other gear working ok

Is there a setting on the MPC to force it to go via the octatrack ? thanks

I should add it works if i disconnect controller mode and stop studio.. but then i lose all instrments!