疑难杂症。求高手解决！！！

我这有俩个dropdownlist。根据选择的第一个 得出下面那个的数据<span class="graytitle">选择表单类别：</span>                <ul class="pageitem">                    <li class="select">                        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" >                        </asp:DropDownList>                        <span class="arrow"></span></li>                    <li class="select">                        <asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged">                        </asp:DropDownList>                        <span class="arrow"></span>                        <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="DropDownList2"                            Display="Dynamic" ErrorMessage="*表单未选择"></asp:RequiredFieldValidator><span style="color: darkgray">*先选择表单类别，再选择表单。</span></li>                </ul>
后台：    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)    {        this.DropDownList2.Items.Clear();        Mobile.DBUtility.DbHelperSQL.BindDropDownList("SELECT DISTINCT A.BillID,A.DocumentName FROM OfficialDocument_Template AS A LEFT OUTER JOIN OfficialDocument_Template_Authorize AS B ON B.CorpID=A.CorpID AND B.BillID=A.BillID LEFT OUTER JOIN LoginUser AS C ON C.CorpID=A.CorpID AND A.UseObjectType=2 AND C.UserID=B.ObjectID AND C.UserID=" + userid + " LEFT OUTER JOIN UserInfo AS D ON D.CorpID=A.CorpID AND A.UseObjectType=1 AND D.UserDepart=B.ObjectID AND D.UserID=" + userid + " RIGHT JOIN (SELECT DISTINCT CorpID,BillID FROM OfficialDocument_Template_Process WHERE CorpID=" + corpid + ") AS E ON E.CorpID=A.CorpID AND E.BillID=A.BillID WHERE A.CorpID=" + corpid + " AND A.DocumentType=" + Convert.ToInt32(this.DropDownList1.SelectedItem.Value.ToString()) + " AND A.DelFlag=0 AND A.IsEnable=1 AND (IsNull(C.CorpID,0)<>0 OR IsNull(D.CorpID,0)<>0 OR A.UseObjectType=0)", this.DropDownList2, "DocumentName", "BillID");    }
我这样设置是可以的。但他只在电脑上的浏览器可以，可在手机上的浏览器运行，就选择了第一个dropdownlist之后 就没反应了。 求高手解决！！！急！！！ DropDownList浏览器