How to make particle system emit?

I am simply trying to get a particle system to emit. I cannot believe how difficult this always is. Unity seems to change the procedure on a monthly basis.

I followed exactly the steps in the docs :

 SprayParticles = ParticlesObject.GetComponent<ParticleSystem>();
 var em = SprayParticles.emission;
 em.enabled = true;

but I am getting the error:

 NullReferenceException: Do not create your own module instances, get them from a ParticleSystem instance

What the heck? As i stated, all i am trying to do is get the emission to be true.