Notes error: Entry found is not a person entry

Using NotesRegistration class to register new user id and hit this error “Notes error: Entry found is not a person entry.”. My finding is that actually there is no person entry with the same first name and last name in the lotus notes address book and found that no person entry document created but then a mail file already created for that person.

Pls advise on the solution to this problem.

Subject: Entry found is not a person entry

REG found a match in $Users for the user in question and it was not a person document. Are you using “enforce unique shortname”? Check the shortname you are using in $Users.

Subject: Entry found is not a person entry

Thanks for your response. Will troubleshoot from the $Users view in the address book.