ช่วยทีครับใส่รูปสถานะใน gridview แล้วพอขึ้น server มัน error

 <asp:TemplateField HeaderText="สถานะ">
                            <ItemTemplate>
                                <asp:Image ID="imChek" runat="server" Width="20px" ImageUrl='<%# Check1(Eval("NewDocid"))%>' />
                            </ItemTemplate>
                            <ItemStyle HorizontalAlign="Center" VerticalAlign="Top" Width="70px" />
                        </asp:TemplateField>

Public Function Check1(ByVal ID As String) As String
        Dim sql As String = String.Format("SELECT * FROM DocList_Approve WHERE DocApNum='{0}' ", ID)
        Dim dr As SqlDataReader = SqlHelper.ExecuteReader(ConnectionString, CommandType.Text, sql)
        If Not dr.HasRows Then
            Return "~/images/no-icon.png"
        Else

            sql = String.Format("SELECT Ap_status FROM DocList_Approve WHERE DocApNum='{0}'and AP_Status=0", ID)
            dr = SqlHelper.ExecuteReader(ConnectionString, CommandType.Text, sql)
            If dr.HasRows Then
                Return "~/images/no-icon.png"
            Else
                Return "~/images/check-icon.png"
            End If
        End If
    End Function