Yamaha DTXpress/DTXplorer/DTXtreme

I bought a Roland fd-7 hi-hat contoller pedal off of eBay and when I 
plugged it into my Yamaha DTXpress module, it didn't work. the hi-
hat trigger always produces the "open" sound even when i press on 
the pedal. I tried reseting the module to its default settings but 
that didn't work. I also tried plugging the pedal into the kick 
trigger jack to see if it would work and it didn't. Are there any 
special settings that I need to use on the Yamaha module to get it 
to accept the Roland pedal? How do I do it?