TextChanged Event Handler not firing when text is deleted

[jwasp]

I create a number of text boxes dynamicallly. ID's are systematically assigned, so ID's stay the same from one instance to the next.

The event handler for textChanged is set as:
tb.TextChanged += new System.EventHandler(this.MyTextBox_TextChanged);

the MyTextBox_TextChanged does not fire when the text in textBox tb is deleted, as opposed to changed from one value to another ...

I used this model to hoping to avoiid sorting and comparing every single comparsion (and hence reduce round-trips to SQL). Any ideas why this would happen?

PS - I've tried both OnInit and Page_Load for creating the textBox(es).