Inverter only runs when when generator runs or shore power.

Yes I know where the inverter is, I know what it powers. The TV and DVD player in the back. I have two house batteries and no matter what position my switches are in, they don't come on or power anything. When I connect to shore power or run the gen, everything works, including the inverter. That is what I expect to work, but the two house batteries should at least power the inverter right? I guess I have some wire tracing to do.