DISA says there was diazapan in my urine.. I take xanex. I looked up both and they are benzo family.how can that be

Welcome to the wonderful world of drug testing.

Diazepam v. Xanax

To properly address your question I need a little more information from you. Specifically:

Who or what is DISA?
Do you have a copy of the results of the test?

Both of these drugs (benzodiazipines) are widely known to cross-react in drug screens. That is to say that a drug screen often confuses one for the other. Confirmatory testing using chromatotography is necessary to properly differentiate.

The more information that you can provide, the greater the chance that I can provide you with a method to successfully dispute an errant result.