Not familiar with the AIX differences but on SCO you don’t get any messages if what you attempt to extract doesn’t match what is on the tape. It only shows successful extracts.
You could make a listing of what is on the tape so you can be sure you are extracting what is stored on it. Try it as tar -tvf /dev/rmt1 > /tmp/tapefiles.
What happens with tar -tvf /dev/mt1 ?
You generally can abort the long process by popping the tape when you get the info you need.

Hi Sammy! First of all thank you for your reply!
That’s the "funny" think, I succeed to make a listing of what is on the tape using the cammand: tar -tvf /dev/rmt1
But when I try to restore .. nothing.

I had suggested the dump to /tmp so you would have a total listing stored rather than having to list it via tar each time you wanted to know the contents.
tar is persnickity (best word I know to describe it) in how it requires input commands.
To get familiar with it I suggest (if you have a blank tape) that you do something like tar -cvf /dev/rmt1 /etc so you can see how it looks and works under conditions you know.
The ./ in front of the files is significant, just don’t remember the causes and how it relates to creating and extracting. You may have help in manual pages, assuming you have them. Try "man tar" and see if something comes up. Everybody ought to know how tar works, but after probably 10 years of using a "super tar" I’ve forgotten most of the details.

Thank you for those interesting ways, Sammy!
I will give a try with a new tape and re-read the f.. manual

And to get help from people who are familiar with the OS and the specific commands for the version you are using might I suggest that you post in one of the unix-aix forum.

can you see any of the file backup extensions; not the individual files?

no cant see anything, but i know there is data on the tapes, veritas just tells me each one is bad media, but i guess its coz it cant read them, as they will have been backed up with some other software i suppose

try this:
Salvagedata Tape data recovery

will give that a look dude, thankyou