Thanks RG, I did read through the user guide, but its still not working…
The drums are Legacy DD501. I only use them as pads to control virtual instruments, so at the moment, I have them plugged directly into my iPad via USB through a USB adapter.
In the track settings, under midi input, I have ‘all inputs’ selected. I’ve used different ‘channel’ settings, because I don’t know what channels its actually referring to. I have the midi through option turned off.