I am getting a permissions error when running this code:

"You do not have permissions to set a value for element defaultaddress due to one of the following reasons: 1) The field is read-only; 2) An associated feature is disabled; 3) The field is available either when a record is created or updated, but not in both cases."

I am able to update employee data through the UI using the same account as for web services.

           EmployeeSearch employeeSearch = new EmployeeSearch();

           EmployeeSearchBasic employeeSearchBasic = new EmployeeSearchBasic();

           SearchStringField fname = new SearchStringField();

           fname.searchValue = "Aaron";

           fname.@operator = SearchStringFieldOperator.contains;

           fname.operatorSpecified = true;

           employeeSearchBasic.firstName = fname;

           employeeSearch.basic = employeeSearchBasic;