Unexpected modified residue

Hi,

I hope this email finds you well.
I am trying to load my protein.pdb file but I encounter the following error:

Your PDB contains an Unknown residue PDBLine: ATOM 552 N HID A 112 -39.022 -24.232 8.677 1.00 10.90 N that should be using HETATM record, please check the HADDOCK library for a list of supported modified residues.

From my knowledge, I do not have any modified residue in my protein structure so this message surprised me. Also, checking on my pdb, this refers to the N of the backbone.
Does anyone know how to fix this problem?

Many thanks,

Valeria

The correct PDB naming for histidine is HIS