Yamaha DTXpress/DTXplorer/DTXtreme

i'm trying to control a softsynth from the dtxpress with no luck.  
i'm not getting any midi coming into the computer.  i'm sure the 
cable is good, as well as the interface . . . is there a menu where i 
must manually turn on midi out?

this kit is here at the studio on loan, so i don't have a manual.

thanks, 
chris deckard
saint louis, moe