song won't convert, "file not found"

I'm sorry if this is ABP but i'm new to the MPC, when i try to make a sequence into a song, it doesn't let me convert it to another sequence, it says 'file not found'

i've tried it loads of times with different sequences and it's happening everytime,

can anyone help?

it works when i repeat it at least once, what if you don't want it repeated at all? anyway to get over that hurdle?