In your situation, When Update Panel2 is refreshed, Update Panel1 won't refresh and so Update Panel1's On Updated will not fire.
Or do the Fad In work manually just like what I have done in the sample below. I think the Update Panel Animation Extender is still full of bugs and not usable in many cases. This causes panel 2 to fade out and disappear and it never comes back because the On Updated event is never fired. If you have two update seperate panels and only want an animation on one you cannot.Either both events need to fire or neither event needs to fire. Lets take this simple animation which is targeted at Update Panel2 If Update Panel 1 updaes it will fire the On Updating animation for Update Panel 2 even though the panels updatemode is declared as conditional.This causes panel 2 to fade out and disappear and it never comes back because the On Updated event is never fired.Demo Page Update Panel Animation Extender is an extender that allows you to play animations both while an Update Panel is updating and after its update is finished.The animations to be played are declaratively specified by using XML.
Update Panel Animation Extender is an extender that allows you to play animations both while an Update Panel is updating and after its update is finished.Accordion Always Visible Control Animation Auto Complete Calendar Cascading Drop Down Collapsible Panel Confirm Button Drag Panel Drop Down Drop Shadow Dynamic Populate Filtered Text Box Hover Menu List Search Masked Edit Modal Popup Mutually Exclusive Check Box No Bot Numeric Up Down Paging Bulleted List Password Strength Popup Control Rating Reorder List Resizable Control Rounded Corners Slider Slide Show Tabs Text Box Watermark Toggle Button Update Panel Animation Validator Callout Release Notes Setup your environment Using a sample extender Creating a new extender Extender base class features Using Animations Animation Reference Automated Testing Cascading Drop Down with a Database Other neat stuff animation plays when every partial postback completes).The animations to be played are declaratively specified using XML.You can read the Using Animations walkthrough for more details about creating these generic animation declarations, as well as other ways to use the animation framework.The framework provides a lot of useful animations to handle movement, resizing, fading, etc.All the animations and their properties are described in the Animation Reference.