CUCM 8.6 Upgrade file not recognised by SUB servers

[balukr]

We have a customer planning to upgrade from CUCM 7.1.3 32900-4 to 8.6.2a, I have downloaded the upgrade file from CCO. When I try to upgrade from OS admin through REMOTE upgrade option with SFTP server, Publisher recognize the 8.6.2 upgrade file but two SUB servers are not seeing those file at all. I have checked compatibility matrix it is supported version for upgrade. I even installed the refresh_upgrade cop file too on all the servers stil no luck have anyone seen this weird issue before..Thanks for your help in advance.

[Gordon Ross]

You have installed 8.6.2a onto the inactive partition on the pub....?

A sub will only let you install a version that is either on the active or inactive partition on the pub.

GTG