c# - Unable to get property 'slice' of undefined or null reference while using datetimepicker.js file -

tried download file http://www.malot.fr/bootstrap-datetimepicker/ , added files datatimepicker.min.css , datatimepicker.js

<div class="col-sm-3 col-lg-2 input-group date">     <%--<asp:calendar runat="server" cssclass="form-control" id="calender"></asp:calendar>--%>     <asp:textbox runat="server" cssclass="form_date" data-date-format="dd mm yyyy" id="fromdate" autopostback="true" ontextchanged="fromdate_textchanged" ></asp:textbox>     <asp:label id="lbldateerror" backcolor="red" runat="server"></asp:label>              </div>