Can't create new user - error shoing 'User already exist''

Can't create new user - error shoing 'User already exist''

HI
I am trying to create a new user but it is not allowing and showing that this user already exist.

However, I can't see this user in 'List of User'. Also 'No of User' shown is equal to users I can see.
user name is nisam@techgalaxy.biz

Thanks