Which kind of restraints did you define to maintain the geometry of the zinc finger?
To get proper results make sure to define distance restraints between:
- all atoms coordinating the zinc (basically define the tetrahedron connecting them
- each coordinating atom and the zinc atom.
Note that the distance restraints must have the zinc atom name between double quotes because of the + in the name.
The correct nomenclature for HADDOCK for the zinc is:
- residue name: ZN2
- atom name: ZN+2 (shifted one character to the left in the PDB file
Also you might use CYF for the cysteines coordinating your zinc (those will not carry the hydrogen on the sulfur)