Register the Assembly

I registered the captcha usercontrol in top of my ascx page
<%@ Register TagPrefix="dnn" Assembly="DotNetNuke" Namespace="DotNetNuke.UI.WebControls"%>

Then I...

Declare the Control like

<dnn:CaptchaControl ID="ctlCaptcha" CaptchaHeight="40" CaptchaWidth="150" 
                    ErrorStyle-CssClass="NormalRed" cssclass="Normal" runat="server" 
                    ErrorMessage="The typed code must match the image, please try again"/>

in code behind...

if (ctlCaptcha.IsValid)
{
    //Do your processing!
}

The problem is : I don't see the image (doesn't render the image). I just see a cross like "image not found".

What am I doing wrong or what am I missing?

thanks

mesut 

DNN 5.4.2 (66)