Please help me, I always receive email report from amanda server like this:

*** A TAPE ERROR OCCURRED: [No writable valid tape found].
Some dumps may have been left in the holding disk.
Run amflush to flush them to tape.
The next tape Amanda expects to use is: intra-15.


STATISTICS:
                          Total       Full      Incr.
                        --------   --------   --------
Estimate Time (hrs:min)    0:00
Run Time (hrs:min)         0:00
Dump Time (hrs:min)        0:00       0:00       0:00
Output Size (meg)           4.3        0.0        4.3
Original Size (meg)         5.3        0.0        5.3
Avg Compressed Size (%)    82.1        --        82.1   (level:#disks ...)
Filesystems Dumped            1          0          1   (2:1)
Avg Dump Rate (k/s)      8794.5        --      8794.5

Tape Time (hrs:min)        0:00       0:00       0:00
Tape Size (meg)             0.0        0.0        0.0
Tape Used (%)               0.0        0.0        0.0
Filesystems Taped             0          0          0

Chunks Taped                  0          0          0
Avg Tp Write Rate (k/s)     --         --         --


DUMP SUMMARY:
                                       DUMPER STATS               TAPER STATS
HOSTNAME     DISK        L ORIG-KB  OUT-KB  COMP%  MMM:SS   KB/s MMM:SS   KB/s
-------------------------- ------------------------------------- -------------
alpha        -r/www/html 2    5420    4450   82.1    0:01 8781.8   N/A    N/A

(brought to you by Amanda version 2.5.0p2)