I have checked the dat file via TrackEditor and I have noticed what may be a problem - gridline.jip is stated to resided in the directory \gp3jams\belini. This may be the cause. You could try creating the directory \belini in the \gp3jams directory and then copy any gridline.jip file into it.
Also try copying the francorchamps directory into the gp3jams directory so you have a copy in both gp3jams and gp3jamsH directories.