X-Frame-Options not working IIS web.config

Question

Our site is not currently safe from clickjacking, so I went into the web.config and added

<system.webServer>
    <httpProtocol>
        <customHeaders>
            <add name="X-Frame-Options" value="DENY" />
        </customHeaders>
    </httpProtocol>
</system.webServer>

This is very straight forward code. My issue is that it's just not working. The questions I have are:

1. Is there a way for me to see if the X-Frame-Options is in the header response? I looked for it with httpfox and got nothing, so I can't verify if the web.config is actually putting things in the header.
2. Why is this not working? What can I do to test or move forward?

I did try to add it in the Global.asax in the Application_Start method, but I cant seem to "hit" this method when I debug; it does not hit breakpoints.

private void Application_Start(object sender, EventArgs e)
{
    // Code that runs on application startup
    HttpContext.Current.Response.AddHeader("x-frame-options", "DENY");

    LogHelper.Info("Cost of Care Web Application Starting");
}

I would like to add that I have tried to add it straight into the head tag and I've also tried to add it in a meta tag like so

<meta http-equiv="X-Frame-Options" content="deny">

Answer 1

Since my comments answered the question here's the end result:

For some reason setting the X-Frame-Options in web.config doesn't seem to actually work even though the documentation makes it sound like it should.

An easy work around is to set the headers manually using:

Response.AddHeader("X-Frame-Options", "DENY");

If you need this set for every request with no exceptions you can add the Application_BeginRequest to Global.asax:

protected void Application_BeginRequest()
{
    Response.AddHeader("X-Frame-Options", "DENY");
}