Unable to remove powerpath dead devices with solaris QFS

Hi Storage Experts,

   i have one solaris 10 host, running QFS filesystem, which had migrated from old volumes to new volumes successfully. However, I am having problem removing powerpath DEAD devices from solaris QFS filesystem, despite all LUNs were unpresented from storage group (Clarrion). After executing powermt remove force dev=emcpower#, it responded with "device still in use", rejected for removal. Then, i tested it with single user mode, still getting the same error message.

  Any advise is highly appreciated, thank you.

Tham