Who's Responsible?

I Started A Job A Few Months Ago In A Nursing Home As An Rn. I Work The Floor Just Like The Lpn's Do. I Was Surprised To Find Out That When We Are Short Nurses For That Shift, (which Is All The Time) We Share Med Carts, As Well As Narcotic Boxes Located On Those Carts. This Means That If We Are Short 1 Nurse, I Share A Narcotic Box With 2 Other Nurses. Pretty Scary! Since I Am The Rn, I Am Usually The One That Has To Count Both Narc Boxes That Are On The Carts While The Other 2 Nurses Also Pass Narcs. The Other Nurses Don't Sign Or Count With Me. Twice It Has Happened That A Narcotic Was Not Signed Out Or Signed In The Wrong Place. Thank God That We Found Where The Narcs Went Both Times, But I Am Very Uncomfortable With This Practice. One Nurse, Suggested That Since We Couldn't Figure Out Where It Went To Just Document "wasted" This Is Not My Kind Of Nursing Practice And I Worked Too Hard To Loose My License Over This. Please Give Me Some Suggestions Or If You Have Ever Heard Of This Kind Of Practice? Am I Just Being Overly Concerned Or Should I Quit And Find Another Job?