You probably are running a version of Dynamo where the Point.PointToNumbers node is not supported, or you have not installed a package (Lunchbox probably ?). Has your graph been developped on a older version of Dynamo ?
Take a look at this : Unresolved Error For Node
hi, Mellouze No more unresolved error after installing lunchbox. I’m very new to dynamo. Thank so much for your reply. It helps a lot.