query volume does not show all used volumes?

I run ADSM 2.1 on an RS/6000 server with a DLT4700 library attached to it.
I have setupt 12 disk volumes of 800MB each, 9 is in a backuppool and
3 in an archivepool. The library (dltautolibpool1) has 7 tape volumes (defined
as scratch voluems, VOL001 through VOL007).

After running backup for a few weeks the status is this:

adsm> query stgpool

Storage      Device       Estimated  %Util  %Migr  High   Low  Next
Pool Name    Class Name    Capacity                Mig%  Mig%  Storage
                               (MB)                            Pool
-----------  ----------  ----------  -----  -----  ----  ----  -----------
ARCHIVEPOOL  DISK           2,400.0   54.3    0.0    50    20  DLTAUTOLIB-
ARCHIVEPOOL  DISK           2,400.0   54.3    0.0    50    20  DLTAUTOLIB-
                                                                POOL1
BACKUPPOOL   DISK           7,200.0   98.0   26.2    50    20  DLTAUTOLIB-
                                                                POOL1
DLTAUTOLIB-  DLTAUTOLI-  4,542,136.    0.5    1.0   100    70
 POOL1        BCLASS1             5


adsm> query volume

Volume Name               Storage      Device      Estimated  %Util   Volume
                          Pool Name    Class Name   Capacity          Status
                                                        (MB)
------------------------  -----------  ----------  ---------  -----  --------
/dev/radsmvol1            ARCHIVEPOOL  DISK            800.0   52.0  On-Line
/dev/radsmvol1            ARCHIVEPOOL  DISK            800.0   52.0  On-Line
/dev/radsmvol10           BACKUPPOOL   DISK            800.0   97.6  On-Line
/dev/radsmvol11           BACKUPPOOL   DISK            800.0   97.5  On-Line
/dev/radsmvol12           ARCHIVEPOOL  DISK            800.0   57.4  On-Line
/dev/radsmvol2            BACKUPPOOL   DISK            800.0   98.2  On-Line
/dev/radsmvol3            BACKUPPOOL   DISK            800.0   99.2  On-Line
/dev/radsmvol4            BACKUPPOOL   DISK            800.0   98.7  On-Line
/dev/radsmvol5            BACKUPPOOL   DISK            800.0   98.4  On-Line
/dev/radsmvol6            BACKUPPOOL   DISK            800.0   97.6  On-Line
/dev/radsmvol7            ARCHIVEPOOL  DISK            800.0   53.4  On-Line
/dev/radsmvol8            BACKUPPOOL   DISK            800.0   97.5  On-Line
/dev/radsmvol9            BACKUPPOOL   DISK            800.0   99.2  On-Line
VOL001                    DLTAUTOLIB-  DLTAUTOLI-   45,421.4   49.7  Filling
                           POOL1        BCLASS1

It seems VOL001 is the only tape volume that has been used, this seems
reasonable. Recently though, I ran backup db:

adsm> backup db type=full devclass=dltautolibclass1
ANR2280I Full database backup started as process 2.

adsm> query process

 Process Process Description  Status
  Number
-------- -------------------- -------------------------------------------------
       1 Expiration           ANR0817I Currently processing file space
       1 Expiration           ANR0817I Currently processing file space
                               /home/martin for node ALBA: have deleted a total
                               of 699 backup files, and 0 archive files.

       2 Database Backup      Full backup: 1280 pages of 68018 backed up.

                               Current output volume: VOL003.


This is confusing. The database backup has been performed to VOL003, but
when I issue query volume I see VOL001 as the only tape volume. How is
this possible?