the MidiRaider's ExpPedal Inputs demand reversed polarity cables.
1. Get yourself a y-cable (6,3mm stereo jack split up in two 6,3mm mono jacks, like this https://m.thomann.de/intl/the_…0.htm?i11l=en_GB%3ADE.EUR ), connect the stereojack to the MidiRaiders expression IN and hook the two mono jacks up to the dunlop's IN and OUT. If you still get malfunction, swap the two mono jacks on the Dunlop's IN and OUT. This should work.
2. Some MissionEngineering Pedals have two Stereo Outs with polarity switches (like this one https://m.thomann.de/intl/miss…EUR&o=9&search=1627678265). This one ye should consider for the MidiRaider.
3. You could also make your own stereo cables with reversed polarity. If you can do basic soldering its not a big business (on one of the jacks, solder tip to ring, the other jack vice versa. ground goes as usual to sleeve on both jacks). Also by far cheaper than buying another ME-Pedal.
Hope this helps,