Having trouble with my baseline

Hey guys! I'm making a beat and decided to make a bassline. Im using SimSynth and the piano roll for this.

Here's the beat: https://www.dropbox.com/s/umlgcrbpzr5cqnc/wiki%C3%A4rweeb.mp3?dl=0

My problem is that the D5 note is for some reason alot lower in volume than the rest of my notes. How do i fix this? They're on the same channel, pattern and everything. You can hear it in the first bar that goes C5-D5 where the C5 is very prominent and the D5 not so much. Thanks for any advice!