Hello again !
Thank you Kambiz for the information. In fact, your component works well ! Delphi seems to have a bug and, sometimes, forgets some folders even if they were listed on the Searching Path/Libraries (Options item of the Tools Menu).
The way I force Delphi to remap correctly folders is to add a dummy folder, save the change, remove this folder, and then compile the unit, and for me it's working (I have a french version of BDS2006).
Hope this help !
PS: Sorry for my poor english