How to model the missing N-terminal residues (Residue number: 1-16) from the protein structure?

My PDB structure consists of residues beginning from residues number 17. We tried modeling the structure using advanced modelling. When the missing residues were given in the loop refine step, there occurred an error stating, "The region cannot be found on the template"

Is there any way you could help us in modelling the missing residues from the N-terminal?

Thanks in advance

Aathithya D

SASTRA University

Thanjavur