ListOrRecordRef not working

Hi,

I'm trying to update a value on a select field but it does not seem to work.

        Customer _cust = new Customer();
        CustomFieldRef[] CustRefList;

                    SelectCustomFieldRef _customSelect = new SelectCustomFieldRef();
                    ListOrRecordRef _listOrRecRef = new ListOrRecordRef();
                    _listOrRecRef.typeId = "820"; //id of the list
                    _listOrRecRef.internalId = "3"; //id of the value in the lsit
                    _customSelect.internalId = "custentity_sales_region"; //id of the field on the customer form
                    _customSelect.value = _listOrRecRef;
                    CustRefList[_customFieldCount] = (CustomFieldRef)_customSelect;

_cust.customFieldList = CustRefList;

Does anyone know what I am doing wrong?