Error in the POSCAR-slab file

[VitHoan]

Dear developers,

I am having a problem with generating the POSCAR-slab file. After calculating surface state, it outputs a POSCAR-slab file (together with other files), but all of the atomic positions in my POSCAR-slab file are NaN in every direction. It seems like other files were not affected; surfdos_l, surfdos_r and other files do not have any error. What could be the reason for this error? And is the calculated surface state still reliable?

Thank you!