Eu quero criar um gráfico de rosquinha do Google preenchido com dados de uma consulta sq

Procurei um código de exemplo, mas não consegui fazer um gráfico aparece

Roteiro

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">
    // Global variable to hold data
        google.load('visualization', '1', { packages: ['corechart'] });
        google.setOnLoadCallback(DrawDonut);

        $(function DrawDonut() {

            var options = {
                pieHole: 0.4,      
                colors: ['#286090', '#d7d7d7']  
            };

            $.ajax({
                type: 'POST',
                dataType: 'json',
                contentType: 'application/json',
                url: 'Default.aspx/GetChartData',
                data: '{}',
                success:
                    function (response) {
                        drawchart(response.d);
                    },

                    error: function () {
                        alert("Error loading data! Please try again.");
                    }
            });
        })
            function drawchart(dataValues) {
            var data = new google.visualization.DataTable();
            data.addColumn('string', 'UnitID');
            data.addColumn('number', 'TotalUse');
            for (var i = 0; i < dataValues.length; i++) {
                data.addRow([dataValues[i].UnitID, dataValues[i].TotalUse]);
            }
            new google.visualization.PieChart(document.getElementById('chart')).
                draw(data, { title: "Use distributed on units" });
        }    
    </script>

Html:

<div id="chart" style="width: 900px; height: 600px;"></div>

Código por trás

<WebMethod()> 
Public Shared Function GetChartData(ByVal MemberIndex As String) As List(Of Object)
    Dim query As String = "SELECT Log.[UnitID], COUNT(*) As [TotalUse] FROM Log WHERE (MemberIndex_Log = @MemberIndex AND (GramSup1 + GramSup2) > 0 AND Log.[UnitID] > 5000) GROUP BY Log.[UnitID]"
    Dim constr As String = ConfigurationManager.ConnectionStrings("DefaultConnection").ConnectionString
    Dim chartData As List(Of Object) = New List(Of Object)()
    chartData.Add(New Object() {"UnitID", "TotalUse"})
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand(query)
            cmd.CommandType = CommandType.Text
            cmd.Connection = con
            cmd.Parameters.AddWithValue("@MemberIndex", Convert.ToInt32(HttpContext.Current.Session("MemberIndex")))
            con.Open()
            Using sdr As SqlDataReader = cmd.ExecuteReader()
                While sdr.Read()
                    chartData.Add(New Object() {sdr("UnitID"), sdr("TotalUse")})
                End While
            End Using

           con.Close()
           Return chartData
        End Using
    End Using
End Function

Eu quero que um gráfico de rosca dinâmico apareça, mostrando o uso das unidades (geralmente de 2 10 unidades) distribuídas no gráfic