The only time I have been drug tested for psych was when I went into the hospital, and they do a full panel.

Your negative test results sound really quite odd if you've been taking the medication, which I am not doubting you at all. There are a few possibilities,

1) The drug testing kits they're using are very weak and non-sensitive. Most expensive drug tests can catch anything even if the urine is watered down by more fluids then normal. So you could have gotten, easily, a false negative.

2) Benzo's can stay in the body for 7-10 days from single use. And up to 30 from regular usage. So if you're taking them, these results seem really quite dodgy.

I went into the hospital, got drug tested and I hadn't taken my clonazepam for two days (depressive episode) and I still tested positive. I would bring this up to your doctor and explain that you want another test, and if they cannot preform a full panel urinalysis, ask to be given a script to go to a lab where they do this specifically.

I hope it all works out!