I am a LTC nurse. To make the back story short, pt has Fentanyl Patch to be changed Q3days, only applied to upper back out of reach, old patch must be discarded(wasted into sharps container) by two nurses & signed in narc book by both nurses. One day, I went to change patch as ordered, the previous patch was not on patient but was signed out in narc book (next to signature reads "old patch wasted" but no co-sign from second nurse). I then found an even older patch. Did full body audit with second nurse, could not locate patch that was supposed to be on pt.. Filled out appropriate med error paperwork, left with supervisory staff.Next day...I am called to director of nursing office. She says "It seems like you only find med errors when per diem nurses work, call me crazy..." I am pretty upset/offended. I am full time on my unit, and yes mistakes happen BUT this mistake is a narcotic error! The nurse who placed the older patch on the pt was a PRN nurse yes, and likely just discarded the new patch innocently. However, that is not my job to figure out. There have been two other occasions where per diem nurses have incorrectly placed the Fentanyl patch on this particular patient IMHO, why is my director coming down on me? I feel the concern should be with the per diem staff members who are not educated on proper placement of the patch!Just wanted some input - would you be offended if your director said this to you? How would you respond? I was dumbstruck, so I just nodded my head at the time.