Custom events on classs: When to bind?

I have a class that raises an event. I use the same instance of the class on both a Page and a UserControl.  I bind both the Page and the Control to the event during Page_Load. But when I raise the event, only the Page's event handler fires.  The "debugs" below end up in a console, and I only see the rebinding debugs from test_event.  The test_event page instantiates a section data object, saves it in Viewstate. It passes by reference to the UserControl, which saves the reference in it's viewstate. I gave each data instance a GUID, so I can confirm that they are both using the same object (not a clone or copy).
What am I doing wrong?
C# Data.cs with event
public event SectionDataDirtyEventHandler SectionDataDirty; public delegate void SectionDataDirtyEventHandler(object sender, System.EventArgs e); public void ReloadData() { // Data was not dirty, and now it is. Let everyone who is ...