No expert on pureC, but;
What do the docs say Logbase() should return, as a type? (EDIT) OK found it and is is type VOIDP, or char* so that should be OK.
Also you haven't declared "handle", Line 5
or work_out in line 8
How do you define the functions you are using, open_vwork(), Getrez(), Logbase()? I don't see any "#include" statements
also "#include <stdio.h>" is missing
Maybe post the full error output.