You have not specified a name for the user event data type.

To correct this error, you must specify a name in the label if the user event data type is a cluster or an individual data element. If the user event data type is a cluster, you must specify unique names for each element.

LabVIEW uses the type name of the element as the name of the user event and as the name of the single data item it carries, which is the same data type as the element. These names are visible when the Event structure handles a user event.