Issue with increasing size of SAN disks on AIX

HI, I have had an issue last night while trying to extend a filesystsem . chvg -g <vg> command cameback with an error

0516-1790 chvg: Failed bootinfo -s hdisk9. 
        Ensure the physical volume is available and try again. 
0516-732 chvg: Unable to change volume group u01vg. 

the VG has 1 filesystem

lslv -l <LV> command
PV                COPIES        IN BAND       DISTRIBUTION 
hdisk9            2659:000:000  20%           533:533:532:532:529 
hdisk10           2658:000:000  20%           533:533:532:532:528 
hdisk36           2658:000:000  20%           533:533:532:532:528 
hdisk37           2658:000:000  20%           533:533:532:532:528 

I have tried umounting the filesystem and varying off and on the VG but same issue.

its a production DB2 database so i really cant easily get outages like this. Any ideas anyone.

---------- Post updated at 07:30 AM ---------- Previous update was at 07:28 AM ----------

its AIX version 6.1 btw and lsvg <vg> command

VOLUME GROUP:       u01vg                    VG IDENTIFIER:  00f6917e00004c000000013214f41318 
VG STATE:           active                   PP SIZE:        128 megabyte(s) 
VG PERMISSION:      read/write               TOTAL PPs:      10652 (1363456 megabytes) 
MAX LVs:            256                      FREE PPs:       19 (2432 megabytes) 
LVs:                1                        USED PPs:       10633 (1361024 megabytes) 
OPEN LVs:           1                        QUORUM:         3 (Enabled) 
TOTAL PVs:          4                        VG DESCRIPTORS: 4 
STALE PVs:          0                        STALE PPs:      0 
ACTIVE PVs:         4                        AUTO ON:        yes 
MAX PPs per VG:     32768                    MAX PVs:        1024 
LTG size (Dynamic): 1024 kilobyte(s)         AUTO SYNC:      no 
HOT SPARE:          no                       BB POLICY:      non-relocatable 
MIRROR POOL STRICT: off 
PV RESTRICTION:     none                     INFINITE RETRY: no

Off the top of my head:

Is this VG part of a HACMP resource group? If yes, it most certainly is varied on in EC mode and "chvg -g" will not work then.

Is hdisk9 available? "bootinfo" will fail if the disk is only in defined state.

I hope this helps.

bakunin