Deepmd lammps error!

[dlProjectYue]

I have trained a dp model and want to validate the results by using lammps to run MD. But when I use an origin script without no errors to run MD, it shows the errors bellow:

The script I use is shown bellow:
compute cchunk all chunk/atom bin/1d z lower ${fraction} units reduced
compute stress all stress/atom NULL
variable press atom -(c_stress[1]+c_stress[2]+c_stress[3])/(3.0vol${fraction})
compute binpress all reduce/chunk cchunk sum v_press
PLEASE HELP ME !

[njzjz]

Please follow the error message.

variable press atom -(c_stress[1]+c_stress[2]+c_stress[3])/(3.0_vol_${fraction})

I don't quite understand here why only the diagonal elements of the stress are used.