seems you are trying to upgrade from local.
check AMP Setup->General->Firmware Upgrade/Reboot Options->Allow firmware upgrades in monitor-only mode is enabled.
upgrade from local:
1. upload needed type firmare to airware. in ur case, for example:
ArubaInstant_Pegasus_6.3.1.8-4.0.0.8_46401
ArubaInstant_Centaurus_6.3.1.8-4.0.0.8_46401
AP version select list will show 6.3.1.8-4.0.0.8_46401.
2. No need to care about update button. this is for upgrade from remote server, in case user don't wanna download IAP image themselves.
3. version select list only display version info without ap type info. user no need to care about ap type if already uploaded all needed type firmware for one version, airwave handle it auto.
upgrade from remote image server:
1. Update button is to update ap firmware version list from remote server. it should be ok to update. after click update button, page hangs for abt 1 mins and responses a message:
List of Aruba Image Versions updated successfully.
or failed message:
Failed to update List of Aruba Image Versions.
2. if user already manual upload firmware to airwave, for example: 4.0.0.7.
then version will display under Local (displayed in Aruba Instant Virtual Controller selecting list),
will not display under Image Server(displayed in Aruba Instant Virtual Controller selecting list).