Will it allow you to make that change manually (without using an iLogic rule)? If it will let you do it manually, then does it show any warning type dialog during that process. If so, you may have to run the rule with its 'Silent Operation' option turned on, to avoid that potential warning or dialog. Also, in your rule code, you are only including the first two inputs being requested. That iPart.ChangeRow method is requesting at least 3 inputs. The third input is an array of Object, indicating some unique row cell values, I believe.
Wesley Crihfield

(Not an Autodesk Employee)