This stupid crap can't open anything without saying "Open failed due to invalid or inconsistent extension type" .spt .x_t .cgr .rpt, or anything else that isn't shitty catpart
check this. file name or file address in your pc will have another type of word which is not in english characters. like ı, ö, ü. etc. this may be problem.
tried renaming it several times, but nothing, nevermind now, Idon't have to do it anymore, thanks anyway :)
lol at your tags, by the way. Have you tried .stp, .igs, .wrl, .stl, .3dxml?