Military stated i failed a drug screen for oxycodone, i've not takin it , how can this happin?

Oxycodone test: Usually the urine test for oxycodone it is not specific and it is listed as 95-97% accurate.Rapidonetm oxy is a one-step, for the detection of the oxycodone drug analyte in urine. It is intended for use in the qualitative detection in urine at the concentration level of 100ng/ml. It is cross reactive with Codeine from cough syrup. 2-4 day in urine, up to 90 days in the hair with chronic use. Gas.