What's wrong with this PL/SQL statement?

declare
cur_sal emp.sal%type;
emp_no emp.empno%type;
min_sal constant number(7,2):=5000.00;
bonus number(4):=100;
count number:=0;
begin
loop
emp_no:=&employeenumber;
count:=count+1;
select sal into cur_sal from emp
where emp_no=employeenumber;
if cur_sal>min_sal then
update emp
set sal:=sal+bonus
where empno=emp_no;
end if;
exit when count=5;
end loop;
end;

The above pl/sql code is to add bonus to employee who had sal>min_sal.... actually this code has to prompt 5 times....but in practically....it prompts for the first time and from next time onwards "emp_no:=&employeenumber" statement omitted and every time only one record will update for 5 times...
for ex: if we enter emp_no as 7964... employee record who had empno 7964 is updating 5 times automatically........yyyyyyyyyyyy?????????????