Matrix Inversion, Gauss-Jordan: Singular Matrix Problem

[Auri]

Hi everyone
I've been stuck here for a month. I want to add ionic liquid to MOF, but after the simulation, it shows: Matrix Inversion, Gauss-Jordan: Singular Matrix.
I tried to modify the molecular definition file and L-J parameters, and also made sure the system is electrically neutral, but the Singular Matrix still appears. I checked the output file and found that the enthalpy is also NaN.
Has anyone encountered this problem?
I'd appreciate any help or advice.
Thanks.