C#  Copy Code
public int RecurrenceIndex { get; }

Visual Basic  Copy Code
Public ReadOnly Property RecurrenceIndex As Integer

 Property Value

At the time the item is being validated, it is still not marked as occurrence and its Item.OccurrenceIndex property returns -1. Therefore you need to use this property to obtain the actual recurrence index of the item. This is done to allow you to change any of the item's properties without forcing it to become an exception.

ValidateOccurrenceEventArgs Members
ValidateOccurrenceEventArgs Class
MindFusion.Scheduling Namespace