Thanks for all of your help. I found the issue. HP-UX lun addressing only supports 0-7 at the unit place.
Let's say the lun is mapped to xyz where z is anything from 8-F, HPUX won't be able to understand it.
so the issue was, device was mapped to 088 lun of the FA port. the 8 at the unit's place was not being identified by HPUX so I had to re-map it to 090 (next available lun after 088) which could then be accepted.
I had to remap and re-mask the lun again with the new configuration.
To check more detail read "EMC Host Connectivity Guide for HP-UX" at page 82.
