Reports & Discoverer :: Getting Error While Printing User Name

following is my code written in formula column

function CF_1FORMULA0006 return Char is
v_user_id number;
u_name varchar2(100);
begin
fnd_profile.get('user_id',v_user_id);

select user_name into u_name from fnd_user
where user_id =v_user_id;
return u_name;
end;

getting no data found error.