DataGrid中采用js为列绑定onblur事件无效

ASPX页面如下：
                                   <table id="Table1" cellspacing="0" cellpadding="0" width="100%" border="0">
                                        <tr>
                                            <td align="center" style="height: 14px">
                                                <asp:Label ID="lblotherfee" runat="server"></asp:Label>
                                            </td>
                                        </tr>
                                        <tr>
                                            <td>
                                                <asp:DataGrid ID="dgdOtherFee" runat="server" AutoGenerateColumns="False" Width="144px">
                                                    <HeaderStyle HorizontalAlign="Center"></HeaderStyle>
                                                    <Columns>
                                                        <asp:BoundColumn DataField="OTHFEEDESC" HeaderText="其他费用">
                                                            <HeaderStyle CssClass="dgheader"></HeaderStyle>
                                                        </asp:BoundColumn>
                                                        <asp:TemplateColumn HeaderText="费率">
                                                            <HeaderStyle CssClass="dgheader"></HeaderStyle>
                                                            <ItemTemplate>
                                                                <asp:TextBox ID="dgirate" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.rate") %>'
                                                                    Width="40px">
                                                                </asp:TextBox>
                                                            </ItemTemplate>
                                                        </asp:TemplateColumn>
                                                        <asp:TemplateColumn HeaderText="费用">
                                                            <HeaderStyle CssClass="dgheader"></HeaderStyle>
                                                            <ItemTemplate>
                                                                <asp:TextBox ID="dgifee" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.fee") %>'
                                                                    Width="40px">
                                                                </asp:TextBox>
                                                            </ItemTemplate>
                                                        </asp:TemplateColumn>
                                                        <asp:BoundColumn Visible="False" DataField="OTHFEEID" ReadOnly="True"></asp:BoundColumn>
                                                    </Columns>
                                                </asp:DataGrid>
                                            </td>
                                        </tr>
                                    </table>
页面效果如下：
 
页面中的js代码如下（采用prototype.js编写）：
    initOtherFeeGrid("dgdOtherFee");
    function initOtherFeeGrid(dgOtherFeeid) {           
            dgOtherFee = $(dgOtherFeeid);
            var row;
            for (var i = 1; i < dgOtherFee.rows.length; i++) {
                row = dgOtherFee.rows[i];
                row.id = "ofee" + i;                bindSingleRowEvent2(row.id);
            }
        }绑定语句如下：
        function bindSingleRowEvent2(rowid) {
            var txtbox = $(rowid).cells[1].childNodes[0];
            txtbox.onblur = calAWBOtherFee;
            //alert(txtbox.onblur)//undefined
            var txtbox1 = $(rowid).cells[2].childNodes[0];
            txtbox1.readOnly = true;
            txtbox1.className = "readonly";
            txtbox.onkeydown = keydownHandler3;        }为什么不能绑定？希望大家一起来探讨一下