this is my code in front-end
<div clss="row"> <div class="col-lg-9 ml-2"> <asp:DropDownList ID="ddlLocations" runat="server" OnSelectedIndexChanged="ddlLocations_SelectedIndexChanged" AutoPostBack="true" class="form-control form-control-sm mb-9"> <asp:ListItem Value="0">Select Locations</asp:ListItem> </asp:DropDownList> </div> </div> <div class="row"> <div class="col-lg-4 mb-2 ml-4 mt-2"> <asp:Label ID="lblCourse" runat="server" Text="Course :"></asp:Label> </div> </div> <div clss="row"> <div class="col-lg-9 ml-2"> <asp:DropDownList ID="ddlCourse" runat="server" class="form-control form-control-sm mb-9"> <asp:ListItem Value="0">Select Course</asp:ListItem> </asp:DropDownList> </div> </div>
this is my code in back-end
protected void ddlLocations_SelectedIndexChanged(object sender, EventArgs e) { BindCourse(); } public void BindCourse() { string mode = null, sp = null; mode = "Location"; sp = "sp_Admission2023Onwords"; DropDownList ddlLocations = (DropDownList)FindControl("ddlLocations"); //if (ddlLocations != null && ddlLocations.SelectedItem != null) { string Location_ID = ddlLocations.SelectedItem.Value; DataSet ds2 = objDal.BindCourse(mode, sp, Location_ID); // ddlCourse.Items.Clear(); ddlCourse.DataSource = ds2.Tables[1]; ddlCourse.DataTextField = "Description"; ddlCourse.DataValueField = "Description"; ddlCourse.DataBind(); ddlCourse.Items.Insert(0, new ListItem("Select Course", "0")); } }
why i am getting this error. Any solution