Hi again
I did a new clean install of sketchup, and that seems to have done the trick
I have tried 2 different files, and both came out with the right type of lines.
I don't know if it was setting that was wrong, that was reset in the new installation, or something went wrong after the first install.
@mitcorb, I tried different styles, and after setting the line type to 1 in some of the styles, the line got thinner, but it was still not the correct linetype in AutoCad, but thank you for your answer
@CHARLIE__V, I tried all different line types in the option, but that did'nt help. Thank you for your reply.