trying to read client certificate, but always return null

[imin]

hi

i used a code i found from another website, to read client's digital certificate:
here's the code (i can't post the code here, since it has too many html tags):

http://forum.java.sun.com/thread.jspa?threadID=744079 

but the output returned is always null....here's the partial output of the above code, when I tried to access my https page using Internet explorer.

javax.servlet.request.key_size not present in this request
 
 
No certificate found, again :(
request authorization type is null
 
request.getAuth ==> null
 
(request.BASIC_AUTH ==> BASIC) 

i really need help to resolve this problem here. been stuck here for a few days.

thanks a lot