Unable to generate topology for my ligand

GROMACS version:
GROMACS modification: Yes/No
Here post your question

Dear GROMACS Forum,

I am encountering issues with creating ligand topologies for my simulations. When I attempt to upload my ligands to generate parameters using CGENFF, I consistently receive errors. This issue occurs in most cases, and I have been unable to resolve it.

Additionally, I have used CHARMM-GUI to generate the ligand topology(using ligand reader and modeler) and included the itp in my topol.top file and the prm file in itp file of ligand( because whenever I included or did not included it in topol.top I got errors about improper dihedral) , but I am still facing errors when running the gmx grompp command. Here is the specific error message I receive:

gmx grompp -f ions.mdp -c solv.gro -p topol.top -o ions.tpr

WARNING: Too few parameters on line of [unl.prm] (source file: toppush.cpp)
ERROR: Atoms in the .top are not numbered consecutively from 1

I have checked the generated topology and parameter files carefully, but I am still unable to resolve the warnings and the fatal error about atom numbering.

Could anyone provide guidance on how to fix this issue or recommend a troubleshooting step I might have missed?