My Mixer doesnt record on the right side

So I mixed a few mixes already.. when i listened to them. I was shocked! Silence on the right side. Let me start from the beginning. So I load a track into a(which is on my left side) then I fade the song to the right(b).. it doesnt record for the right side!!! I tried to figure it why this is happening.. I read the complete manual and searched it here.. I hear complete silence on the right side when I listen to my recorded mix. I want to use my U-Mix Control Pro to record mixes using my headfones. I dont want any speakers function.. Please tell me what to do.. One more question.. when you want to listen the song on the right while the left is still playing.. u click source b right? so it doesnt record.. Please help me guys