Sean:--On top end plumbing fixtures, you can expect top end operation. If you are experiencing difficulties with less than that, call the 800 number for the manufacturer. I'm sure that they will be delighted to supply you with whatever information or support needed to solve the problem.
As for the post from Tex on this issue... Without a little humor,(especially in the Plumbing Profession) life can become pretty monotonous and grim. I'm sure it was well intentioned..as a matter of fact I think I'll see if that thing is still available. Lots of luck with your shower.....Bud