... and you have made sure that note numbers correspond between the two machines?
You can confirm what the KSP is really sending by opening the MCC and turning on the MIDI debugger pane (sorry, forget what they call it but it's under one of the menu options). Make sure the note numbers shown match what the Drumbrute expects.
It's also worth switching the KSP track assigned to the drum brute (track 1 right) to "sequence" and then manually play every note from 0 to 127 to see if any trigger the drum brute. If none do then it's got to be that the channel setup is wrong on one device or the other.
This is great advice. Every drum machine responds to a different midi note number, for each drum sound and the default for the KSP, may be different, then what the Drumbrute is expecting. I highly doubt there is an incompatibility, between two main devices, from the same company. Look into the midi implementation chart for the Drumbrute and create a custom drum map to make sure each of the 24 tracks on the KSP, properly relates to the pads on the Drumbrute, midi note number wise. As synthcreep mentioned, if you go into regular sequencer mode and not drum mode, you have access to all midi note numbers in one shot, press all the keys and see if any of them trigger off a drum sound from the Drumbrute, if so, you know it is working and it just a means of creating a proper drum map, so they can communicate properly. My original TR-707 from 1985 responds from the KSP, after creating a proper drum map, so I would like to think your very modern Drumbrute, from the same manufacturer of the KSP, will do so.
All the best. I know these are frustrating situations. I have been there many times myself and it is very unmotivating and time wasting.