error returned for a query containg case

THIS IS MY TABLE

EMPNO JOB MANAGER
========= =============== ==============
101 ENGINEER ASAD
102 ACCOUNTANT ARJUN
103 OFFICEBOY KIRAN
111 DRIVER VARUN
104 LIFT OPERATOR CHRISTY

since the table is not clear here i will explain
the table contains an empno column of integer type,job column of varchar type and a manager column of varchar type with the shown values


THIS WAS MY QUERY
select case
when((select count(empno) from employee where manager='asad')=1)then 'more than one employee'
else(select empno from employee where manager='arjun')
end
from employee where manager='arjun'
AND THE FOLLOWING WAS THE ERROR SHOWN FOR THE ABOVE QUERYConversion failed when converting the varchar value 'more than one employee' to data type int.
THANKS IN ADVANCE ........ FOR HELP