I found that there is missing functions in the tutorial02.
In the function 'templateLoading', these are missing.
sio2ResourceBindAllImages( sio2->_SIO2resource );
sio2ResourceBindAllMaterials( sio2->_SIO2resource );
The tutorial02 works well with the included tutorial02.sio2, but it does not with the other models that have texture images. After I added them, now the tutorial works fine.
Compare the procedure with the one in the Tutorial04.
Update: Well, the tutorial02 is about just using 3D models, which has no textures. So, the tutorial code is not a bug, actually.