Most likely a permissions problem, but it is impossible to tell given the information you have provided. You should run (as root) the command "kextload -t -n kerneltest001.kext" & "kextload -t -n HelloIOKit.kext" and examine the resulting messages. If they say something about "Kext not authentic", you should make sure their permissions are read-only and ownership is root:wheel. You can use the commands: chown -R root:wheel kerneltest001.kext HelloIOKit.kext chmod -R go-w kerneltest001.kext HelloIOKit.kext to fix up the permissions. This is documented at http://developer.apple.com/documentation/ReleaseNotes/Darwin/ KernelExtensions.html There may be other problems, but this is the most common. Cheers, - Dean On Apr 13, 2004, at 11:21 PM, yetty wrote: Dear Sir/Madam, I am trying kernel programming on Mac OS X. I have read the following 3 papers: Kernel Extension Dependencies Creating a DeviceDriver With Project Builder Packaging Your KEXT for Distribution and Installation And I have write two kernel programs. One is accroding to Kernel Extension Dependencies and I name the project as kerneltest001. The other is accroding to Creating a DeviceDriver With Project Builder and I name the project HelloIOKit. After I have finished packaging and installing the projects,I can find them on window of "system.profile->Extensions". On the top of this window there are four column. On the first column there many .kext files such as ACard62xxM.kext,ACard671xSCSI.kext .My project kerneltest001.kext and HelloIOKit.kext are also there. But on the fourth column says that my kerneltest001.kext and HelloIOKit.kext are "You can not use", why? yours sincerely user of Mac _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.