CP214 Notice - for terminated plan

I called the IRS and asked them why I keep getting this notice as I already filed the final 5500-EZ plan 5 years ago. They ask me to take a look at my 5500-EZ form. They told me when I file the final 5500-EZ form on my "total number of participants at the end of the plan year" I need to put "0" and not 1. I filled out everything else correctly I put final return, first return ( it was my first) and end of year I put 0 assets. But who would have known that the total participants at end of the plan year need to be 0. and this is what is causing them to mail me a form yearly. I hope the IRS agent is right. He claims I won't be hit with any penalty because my assets was $0 and I filed on-time but I need to file an amendment so they won't keep sending me these CP214 notices annually