The Kohn Sham matrix is not 100% occupied

[Claudio]

Dear all, when I try to run a periodic HF calculation or a mixed HF
DFT run (b3lyp) for example. I always get

 *** 06:49:15 WARNING in
hfx_energy_potential:integrate_four_center         ***
 *** err=-300  The Kohn Sham matrix is not 100% occupied. This may
result   ***
 *** in uncorrect Hartree-Fock results. Try to decrease EPS_PGF_ORB in
the  ***
 *** QS
section.
***

Same system converges without problem without HF using for example
PBE. I tried decreasing EPS_PGF_ORB and EPS_DEFAULT without much
success. I also tried decreasing basis set size. I am not using a
truncated potential.

Is this warning relevant? I am having a very hard time converging the
b3lyp calculation.

Thanks,
Claudio