Property let procedure not defined and property get procedure did not return an object (Error 451)

Certain properties, methods, and operations can only apply to Collection objects. This error has the following cause and solution:

• You specified an operation or property that is exclusive to collections, but the object isn't a collection.

  Check the spelling of the object or property name, or verify that the object is a Collection object. Also look at the Add method used to add the object to the collection to be sure the syntax is correct and that any identifiers were spelled correctly.

For additional information, select the item in question and press F1 (in Windows) or HELP (on the Macintosh).