Infinite particle duration

Can’t seem to get my particle system to go forever. It always stops after a few seconds
Probably the same issue as this

I’ve typed infinity into my Duration parameter (which then changes to 100,000), and tried with both Looping enabled and not enabled. No difference.

Anyone have an idea? is this possibly a bug in Unity 5?

I hope you got your answer, still for others who are looking for this.
You should increment the value of “Start lifetime” rather than 'Duration". Start lifetime is the total time for which particle will live whereas duration is the length of time the particle system is emitting particles.