2013 NGS NY State Medicare Denial for CPT® 31231 & 31575 NP

Has anyone encountered denial code CO B7 in new york state for nurse practitioner billing for CPT® 31231 or 31575? Apparently the denial is for not in their scope of practice beginning January 2013. When I contacted Medicare that's the only reason they would give me for the denial and directed me to ngs.com to search for the new rule. We are an ent office and she has been paid for this in the past when directly billing under her as should be for a new patient.
Would anyone have a suggestion of where I might locate this new rule and if I have a reason for appeal?
Thank You

re: 2013 NGS NY State Medicare Denial for CPT® 31231 & 31575 NP

Did you look for any MLN's? I have heard that it is not billable unless performed by the physician but I have not searched for the "new rule" yet.