alt_disk_install is failing

[mainakdas73]

I am facing a problem while running alt_disk_install and the following error is given below :

Building boot image on cloned disk.
forced unmount of /alt_inst/var
forced unmount of /alt_inst/usr
forced unmount of /alt_inst/tmp
forced unmount of /alt_inst/oracle
forced unmount of /alt_inst/opt
forced unmount of /alt_inst/home
forced unmount of /alt_inst
forced unmount of /alt_inst
Changing logical volume names in volume group descriptor area.
0516-082 /usr/sbin/lchangelv: Unable to access a special device file.
Execute redefinevg and synclvodm to build correct environment.
0505-121 alt_disk_install: Error.

can any body please help me regarding this and thanks in advance for your help.