I am having the same problem. I made sure that my file extension was .c and not .wdl. I added acknex.h along with the supplementary files and this is the error I'm getting:
< #include <litec.h> #include <compat.h> typedef fixed var;>
acknex.h 10:0 (): Script error - no C code in .WDL scripts!
< typedef fixed function;>
acknex.h 11:0 (): Keyword unknown typedef
< typedef void action;>
acknex.h 12:0 (): Keyword unknown typedef
< #include <atypes.h> #define EXT #define F(f) f #define afuncs_dll_h>
acknex.h 24:0 (): Script error - no C code in .WDL scripts!
< STRING* txt_str^TEXT*);>
acknex.h 31:3 (): Syntax error - TEXT* invalid character *