i am currently on random drug screens for work. I do have a script for Xanax which has been approved for me to take due to me being on multiple asthma medications. However 2 recent drug screen results show that Ativan was in my system, which I have never taken. Could this be an error? And can urine drug screens really differentiate between benzos. The board of nursing is attempting to revoke my licence due to this discrepancy. Please advise.