Watch the 1-5-6-4 Reggae #1 online guitar lesson by Andrew Ford from Bass Groove Survival Guide

Lets break this one down and play it a little slower, make sure you get a nice swing with the 16th note in bar 4. This is one of those cases where I would use the one finger per fret fingering so all notes in bar 1 can be played without shifting. Same for bar 2.