asp.net ajax control toolkit slideextender step 1 not functioning

while using ajax control toolkit slideextender,

found that it is not functioning,

while using 10 it is functioning

<asp:SliderExtender ID="SliderExtender1" runat="server"
    TargetControlID="txt01"
    Minimum="-100"
    Maximum="100"
    BoundControlID="txt02"
    Steps="1" /><asp:TextBox ID="txt01" runat="server"></asp:TextBox><br /><asp:TextBox ID="txt02" runat="server" ontextchanged="TextBox2_TextChanged" AutoPostBack="true" ></asp:TextBox>


    protected void TextBox2_TextChanged(object sender, EventArgs e)
    {
        ClientScriptManager cs = this.ClientScript;
        cs.RegisterStartupScript(this.GetType(), "changesize", "document.getElementById('TextBox2').size = document.getElementById('TextBox2').value;", true);
    }