MIDI connection Fails

Hi there.........
I'm trying to connect my Sp-808 to a Yamaha DTXpress Drum Module........ so I can play some samples trough my drum pads.
I've connected them with a MIDI cable.........MIDI OUT of DTX Module to MIDI IN of the black box.........and nothing happened........ I've changed some settings...and nothing......I happend to have a Yamaha Synth....... and as I was bored trying to trigger some samples from the Sp-808 having no result at all........I started toying with my Synth.......so I played some sounds of the Synth with my Pads......I ¡ve connected MIDI Out of Drum Module to MIDI in of Synth....after a while I added anothrt MIDI cable from MIDI Trough of the Synth to MIDI IN of SAMPLER..........and.......it worked....... I don¡t know what a hell happened.....but it worked..........
My question is.........does anybody experienced something like this?? If yes or not........does anybody knows how to eliminate the Synth from this chain, beacause its pretty anoying to carry a Synth just to use the MIDI Trough connection tp perform live...........
Thanx in advance.
Alex