编译错误 - 您是否缺少 using 指令或程序集引用？

Question

After i debug the program, the page show me the following error. I have no idea to solve this error, is that missing the assemblies ?

Here is the error their show:

Compilation Error

Description : An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message : CS1061: 'ASP.dcbrequestlogcriteria_aspx' does not contain a definition for 'ddlTelco_SelectedIndexChanged' and no extension method 'ddlTelco_SelectedIndexChanged' accepting a first argument of type 'ASP.dcbrequestlogcriteria_aspx' could be found (are you missing a using directive or an assembly reference?)

Source Error:

<span class="fieldlable">Telco:</span>
<span>
<asp:DropDownList ID="ddlTelco" runat="server" DataTextField="Text" DataValueField="Value"  AutoPostBack="true" OnSelectedIndexChanged="ddlTelco_SelectedIndexChanged" SelectMethod="LoadTelco"  Enabled="false"></asp:DropDownList>
</span>
<asp:RequiredFieldValidator ID="RequiredFieldValidatorTelco" runat="server" ErrorMessage="Telco" ControlToValidate="ddlTelco"></asp:RequiredFieldValidator>

Answer 1

You have assigned the event handler ddlTelco_SelectedIndexChanged to the OnSelectedIndexChanged event of the DropDownList But you forgot to define it in the back-end, or it may be deleted.

If you really want to do something with OnSelectedIndexChanged define ddlTelco_SelectedIndexChanged in the back end and rebuild the solution . If you don't want means remove OnSelectedIndexChanged from the markup

Answer 2

It means that it is looking for the event ddlTelco_SelectedIndexChanged which you have subscribed to your control

On the code behind of your markup, define an event for ddlTelco_SelectedIndexChanged or by subscribing your control to an event and generate

ddlTelco.OnSelectedIndexChanged += ddlTelco_SelectedIndexChanged

    protected void ddlTelco_SelectedIndexChanged(object sender, EventArgs e)
    {
    //Write implementation here
    }

and rebuild.