HELP !!! ontape -r failed

My customer has RS6000 F40 AIX 4.1 and I-OWS 7.20.UC2. All I know about tape drive is: that is 4 mm DDS-2 tape auto loader RRR6137. SMIT parameters are Tape Drive rmt0 Tape Drive type scsd Tape Drive interface scsi Description SCSI 4mm Tape Drive Status Available Location 04-A0-00-6,0 Parent adapter scsi0 Connection address 6,0 BLOCK size (0=variable length) [0] Use DEVICE BUFFERS during writes yes RETENSION on tape change or reset no DENSITY setting #1 36 DENSITY setting #2 19 Use EXTENDED file marks yes Use data COMPRESSION yes and INFORMIX are # System Archive Tape Device TAPEDEV /dev/rmt0 TAPEBLK 16 # Tape block size (Kbytes) TAPESIZE 4096000 # Maximum amount of data to put on tape (Kbytes) # Log Archive Tape Device LTAPEDEV /dev/rmt0 LTAPEBLK 16 # Log tape block size (Kbytes) LTAPESIZE 4096000 # Max amount of data to put on log tape (Kbytes) We can't do restore with ontape -r Here is what happens: After the question: Do you want to back up the logs (y/n) we say y(es). We get the following WARNING: TAPEDEV and LTAPEDEV are the same, tape device is '/dev/rmt0'. You must change tape to avoid overwrite of current archive tape. Please mount tape 1 on /dev/rmt0 and press Return to continue ... We change tapes (unload archive tape and load new tape manually. Wait for READY message on display) and press Return key. Would you like to backup any of logs 355-454? (y/n) y Logical logs 355 - 454 may be backed up. Enter the id of oldest log that you would like to backup? 355 Please label this tape as number 1 in the log tape sequence. This tape contains the following logical logs: 355-454 Log salvage is complete, continuing restore of archive. Please mount tape 1 on /dev/rmt0 and press Return to continue ... We change tapes (unload logical log tape and load archive tape manually. Wait for READY message on display) and press Return key. Physical restore failed - function read archive backup failed code -1 errno 9 We tried that several times and we didn't make mistake in tape manipulation. If we make only restore (without backing up logs) with same archive tape we get no errors. Same error happens if we don't make backup of logs at time of restore and after the restoring from archive tape we want to continue restore from logical logs backup (we unload Archive tape, load tape with logical logs that was backed up with ontape -a, press Return and get error message from above). What is wrong ? HELP !!!