Do you mean that you had to suck hard to get air through it? If so that will be your placing of the cotton wool. If you mean you got no vapour, that will be just a case of the material not warming through properly either due to placement, lots of cotton or the location of the drops on the wool. It just takes experimentation to get used to using it the way you like it.
Removing the lower screen is good because firstly it does nothing but get messy and is hard to cleam, and secondly it stops you pushing the cotton down into the very bottom of the bowl where it is best placed.
Removing the lower screen is good because firstly it does nothing but get messy and is hard to cleam, and secondly it stops you pushing the cotton down into the very bottom of the bowl where it is best placed.