yamaha ydd 60 midi issue

[junray]

hi,
i'm new to the forum.
i have a problem trying to play my yamaha ydd 60 in cubase using a vst drum sampler.
i've read several threads in the forum trying to find the solutioin, but nothing worked.
the software receive the midi signal, i remapped the drum map, but i can hear the sound just sometimes. i mean that hitting the pad it doesn't give out the sound everytime i hit it, but just sometimes.
i thought it was matter of velocity, but i didn't find out how to handle it, and what to set to avoid that issue.
could u please help me with that?