Could it be that the two proteins are too far from each other?

I realized it was due to protein size, 1270 AA folded in 3 chains.

I recommend using ClusPro, HDOCK or HEX servers for protein-protein docking.

Thank Arturo Rojo for your recommendation, I have tried to use cluspro, but the problem is, Cluspro generated PDB models do not allow me to carry out extra analysis, for example to check Protein protein interactions.