if your not observed u should substitute...if u are observed just dilute and pray ...they dont ALWAYS ua on probation appts....and if your lucky yer PO will give u a heads up... i know mine will always say shit to me in the previous meeting to let me know a UA will be commin up...last month she told me "make sure u stay clean this month" and sure enough i got a ua last week....anyways... GOOD LUCK ...i feel for ya...i hate probation