Cool, thanks Christophe.
That's showing a lot more useful information.

In the folder "/home/toto/salasaga/screenshot", there are several screen shot files with names like "screenshot001.png", "screenshot002.png", and so on.
I'm not sure, but I suspect they were created with one of the previous versions of Salasaga we've been trying.
If you create new screen shots, they should still be going into this folder, but they're probably named differently.
Can you please take another screen shot with this version of Salasaga, then check if a new file is created with a completely different file name? I'm suspecting it will be created with the translated words for "screen shot".
It's also possible it might be looking for that file name when importing, so the new screen shot might be imported, but the older "wrongly named" ones might be getting ignored.
?