You need to use an upgrade file, not the bootable file that you use for fresh installation. You can either request it through the PUT tool or you can download it from the following link
thank you for your reply
i already used this file (UCSInstall_UCOS_22.214.171.12400-28.sgn.iso) but after starting the upgrade it stck there for 6 hrs.
Then i cancelled upgrade process.
Please ensure that you meet the hardware requirements for cucm version 9.1. If that is in place then please reboot the Publisher and attempt the upgrade again and provide the install logs if the upgrade fails.