set focus not working any how....

Hi,
 
my page contains ---master page and in master page contains-updatepanel--updatepanelanimationextender...
 
i have try all the way that mention below but not worked for me...if you have any other solution than let me know....
 
((ScriptManager)Page.Master.FindControl("ScriptManager1")).SetFocus((TextBox)InsertSearchPnl.FindControl("CanTxt"));
 
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string script = "document.getElementById('" + CanTxt.ClientID + "').focus();";
 
script = script + " WebForm_AutoFocus('" + CanTxt.ClientID + "');";