problem with criticality of key usage extension

Hi everybody, I'm instaling a subca and I'm submitting the request to a standalone CA. I need to make the key usage extension of the subca certificate critical, to do so after I submitted the request, I run this command

certutil -setextension  Request_ID 2.5.29.15 1 @File_Name.txt

(exactly as what is said in the article below), but after the standalone ca issues the request, the key usage extension is not marked as critical.

http://support.microsoft.com/kb/888180

plaese help me solve this problem, thank you.