forward declaration of struct TagLib::Tag error

[Amr Hassan]

i'm trying to use taglib in a qt project from eclipse, everytime i try 
to compile after adding the header file <fileref.h> i get this error at 
compilation:

Severity and Description    Path    Resource    Location    Creation 
Time    Id
make: *** [release] Error 2        projName    line 0    
1206157042015    1704
make[1]: *** [release/Track.o] Error 1        projName    line 0    
1206157042015    1703
forward declaration of `struct TagLib::Tag'    
projName/taglib/include    tfile.h    line 36    1206157042015    1702
invalid use of undefined type `struct TagLib::Tag'    projName/core    
Track.cpp    line 116    1206157042015    1701


what's happening here?!