Accepts my queryHit with the calculated sha1 and asks for the file and i even finish DL, and the file is fine. I don't know what the f#$% is gtk-gnutella's problem with this sha1, but i can't keep hitting my head against that wall (metaphoric wall, of course, i took my pills today!).
So the file is fine - just gtk-gnutella doesn't allow me to give this sha1 for some reason.

Thanks for your always-rapid response, and of course your help.
If i ever will be able to find why gtk-gnutella doesn't accept this sha1 i'll post it.