Gromacs error

Hi all,
I am getting an error while running with Charmm36 force field in gromacs.

Program: gmx pdb2gmx, version 2020.1-Ubuntu-2020.1-1
Source file: src/gromacs/gmxpreprocess/pdb2gmx.cpp (line 745)

Fatal error:
Atom OT in residue LYS 200 was not found in rtp entry LYS with 22 atoms
while sorting atoms.

For more information and tips for troubleshooting, please check the GROMACS
website at Errors - Gromacs

can anyone help me out in this regard?