Midi notes wont fire simultaneously

[drewf2]

I have an issue with midi in pro tools 10. I am using steven slate as an insert to an instrument track in pro tools, where i write midi drums. The problem is when two or more midi notes are played at the same time (like a kick and cymbal) on the grid only one will sound. If i slightly nudge one note so they are not perfectly in line then both sound (refer screenshot attached).

Steven slate only picks up one note being triggered so it is definitely a pro tools issue not the drum program. I am sure this is an easy fix but for some reason everything I try has not helped! Any advice would be greatly appreciated.