[chimerax-users] Measuring contact area in a pdb file

Dear ChimeraX Developers, I was wondering if you could explain to me how to measure the contact residues/area in a pdb file containing an antibody and antigen? I have been trying to do either measure buriedArea or contactArea, but I get an error. I have been using the PDB file 7Y0W as a starter structure to then use for future structures. Let me know if you need anything else. Thank you for all your help. Geoffrey Shimberg