Ok thanks you all... it worked.

STRING* test_str = "";

is indeed necessary, but the error message I got: “invalid pointer or handle in a function” was about something else....

somehow I saved the file: test.txt as test.txt.txt, this kind of file name is allowed by Vista (strange??) but not by Lite c of course. To make simple things more complicated Vista explorer did doew not show the file extension, so I just saw test.txt, only when I made a second text file I saw my mistake.... I really feel like a beginner, thanks anyway.