I have received error while running mmpbsa command

"gmx_MMPBSA -O -i mmpbsa.in -cs gromacs.pdb -ct traj.xtc -ci index.ndx -cg 1 13 -cp gromacs.top -o FINAL_RESULTS_MMPBSA.dat -eo FINAL_RESULTS_MMPBSA.csv"

error:

[WARNING] Number of decomp residues to print using print_res = 'within 6' < 2 [INFO ] Increasing cutoff value by 0.1 until number of decomp residues to print >= 2 [ERROR ] MMPBSA_Error The maximum number of iterations to select interaction residues was reached.

Please set print_res with a valid selection.

KIndly help me in rectifying this issue