Validation for FileUpload control

Question

I need to make validation message for file upload when a user click on the button without uploading file the error message appears

This the code I have tried but it is not working

 

 

<asp:FileUpload ID="FileUpload1" runat="server" Width="200px" OnLoad="FileUpload1_Load" />

<span runat="server" style="color: red; font-size: 20px">*</span>

<asp:RequiredFieldValidator ErrorMessage="Video title is a required field."

ID="RequiredFieldValidator11" ForeColor="Red" ControlToValidate="FileUpload1"

runat="server" ValidationGroup="click" SetFocusOnError="true" />

Please help