Trying to set the updatepanel value in jquery but not working

[killerandres]

I want to set the style on asp.net UpdatePanel in JQuery which is the child of div element. I put the following code inside the window.onload event but does not work. But when I put it \[code\]Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequestHandler);\[/code\]Here then it works. The code is:\[code\]$("#divmanipulation > :first-child").css({'float':'left'});\[/code\]