Undesired Ajax calendar extender focus on postback

Hi guys,
I have a child page that inherits a master page. The child page contains a text box, that has a calendar extender, working fine when you click on textbox.  However, everytime there's a postback, page focuses on the calendar textbox control causing the calendar to popup on every postbacks.  

I have tried the following to remove the focus on this control:
1) Changed the tab index = 3 because it is the 3rd control on the page from the top.
2) Used .focus property on other controls on the pageload event. Ex: txtOther.focus()
2) Tried setting to focus to other controls on the pageload event programatically using the script attached with no luck.  Ex: SetFocus(txtOther)

Thank you for your help.

Private Overloads Sub SetFocus(ByVal control As Control)
            Dim sb As New StringBuilder()

            sb.Append(vbCr & vbLf & "<script language='JavaScript'>" & vbCr & vbLf)
            'sb.Append("<!--" & vbCr & vbLf)
            sb.Append("function SetFocus()" & vbCr & vbLf)
            sb.Append("{" & vbCr & vbLf)
            sb.Append(vbTab & "document.")

            Dim p As Control = control.Parent
            While Not (TypeOf p Is System.Web.UI.HtmlControls.HtmlForm)
                p = p.Parent
            End While

            sb.Append(p.ClientID)
            sb.Append("['")
            sb.Append(control.UniqueID)
            sb.Append("'].focus();" & vbCr & vbLf)

            sb.Append("}" & vbCr & vbLf)
            sb.Append("window.onload = SetFocus;" & vbCr & vbLf)
            sb.Append("</script>")

          
End Sub

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Private Overloads Sub SetFocus(ByVal control As Control)
            Dim sb As New StringBuilder()

            sb.Append(vbCr & vbLf & "<script language='JavaScript'>" & vbCr & vbLf)
            'sb.Append("<!--" & vbCr & vbLf)
            sb.Append("function SetFocus()" & vbCr & vbLf)
            sb.Append("{" & vbCr & vbLf)
            sb.Append(vbTab & "document.")

            Dim p As Control = control.Parent
            While Not (TypeOf p Is System.Web.UI.HtmlControls.HtmlForm)
                p = p.Parent
            End While

            sb.Append(p.ClientID)
            sb.Append("['")
            sb.Append(control.UniqueID)
            sb.Append("'].focus();" & vbCr & vbLf)

            sb.Append("}" & vbCr & vbLf)
            sb.Append("window.onload = SetFocus;" & vbCr & vbLf)
            sb.Append("</script>")

          
End Sub

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