DP-02CF low volume issue

[FAlameda]

Hi, new here. have a problem with getting any volume on my B channel. try to explain, if I am trying to record on track A only I have great volume on my headphones and on the track I record on. When I switch over to B only I can hardly hear my headphones and very faint recording on track. If I have both inputs on I get good volume. Trying to figure out what Im doing wrong, anyone know this machine and have any ideas? Thanks Frank