UP clock signals with 27MHz input

No, basically the clock signals core requires a 27MHz signal to generate the audio clock but i cannot get the audio chip to work at all using this clock.

I can only get the audio codec to work when driven by a ALTPLL core with 50MHz input.

What i am asking is, do i need to do anything else to use the 27MHz crystal? i'm only thinking this because it looks like the 27MHz crystal is connected to the video chip.

maybe i should just stick with using ALTPLL, it seems to work fine i guess