Error of generating tetrahedral mesh for volumic elements

Hello,

I am trying to generate some volumic elements using SOV and SVOB (see my Teddy code below):

+PROG SOFIMSHC
HEAD Test
SYST REST
CTRL TOLG 0.001
CTRL MESH 3
CTRL HMIN 0.1
CTRL PROG 2

SVO 1 GRP 1 MNO
SVOB TYPE OUT NO 1
SVOB TYPE OUT NO 2

END

It was fine for almost elements except one with an error saying: “Error generating a tetrahedral mesh”.
I’ve tried to reduce the HMIN and raise TOLG up to 0.01, but nothing works.