Buzz Lightbeer
Bluelight Crew
I had looked this up some time before, my suspicion was confirmed seeing that I had visited the link before 
Page 11, section F

Page 11, section F
Typically, the parent molecule is used as the analytical target and it has been observed that various immunoanalysis assays developed for detecting amfetamine and methamfetamine-type drugs might not be able to generate a positive finding for DOC (7-12) due to lack of sufficient cross-reactivity (exception: 33% in one particular amfetamine test kit (13)), thus, potentially leading to false negative findings