Anybody have any ideas on this?

I have a user defined type that has a couple of text propeties.   I have a dynamic update panel with the following inside it:
I have a webform that has two text boxes on it.  Both have Post Form on Value Change checked.  I also have an embedded action button and a grid below it.
The embedded action button has an action model that takes the values entered in the text boxes and add them to the collection of the user defined type. 
The grid displays the value of that collection.

When I enter something in the text boxes and then click the embedded action button nothing happens.  but when I press it again the grid displays the data entered.  It looks as if when I click the embedded action button the post back is firing and does not fire the action model.  

I have tried adding java script that on leave focus of the text box it fires a postback, but I can't get that to work.

Anybody had any luck doing something similar?

I don't want to have to have my users click the button twice.