Cookie in asp.net mvc not setting

Question

I am experiencing strange situation. The set cookie is persisted only when the string is hard coded.

public void OnActionExecuted(ActionExecutedContext filterContext)
{
    if (filterContext.HttpContext.Items["Theam"] != null)
    {
        var sTheam = filterContext.HttpContext.Items["Theam"].ToString();

        HttpCookie theamCookie = new HttpCookie("TheamCookie");

        theamCookie.Values.Add("TheamVal", sTheam);
        theamCookie.Expires = DateTime.UtcNow.AddDays(5);
        HttpContext.Current.Response.Cookies.Add(theamCookie);
    }
}

No mater what I do the cookie is not persisted. Only when replace sTheam to a value like "cupid" the value is persisted. That is

theamCookie.Values.Add("TheamVal", "cupid"); 

works and nothing else.

Can any one throw some light as to what is happening? I am exhausted, and completely ran out of options. After over 8 hours of debugging that I realized this. But not sure why is this happening. Please help.

Update: The following is the CookieFilter. This is an ASP.NET MVC app.

public class CookieFilter : IActionFilter
{
    //private const string sTheamCookieName = "TheamCookie";
    public void OnActionExecuted(ActionExecutedContext filterContext)
    {
        if (filterContext.HttpContext.Items["TheamToBrowser"] != null)
        {
            var sTheam = ((string)(filterContext.HttpContext.Items["TheamToBrowser"])).ToString(CultureInfo.InvariantCulture);

            HttpCookie theamCookie = new HttpCookie("TheamCookie");


            theamCookie.Values["TheamVal"] = "shamrock";
            theamCookie.Expires = DateTime.UtcNow.AddDays(5);
            filterContext.HttpContext.Response.Cookies.Add(theamCookie);
        }
    }

    public void OnActionExecuting(ActionExecutingContext filterContext)
    {
        HttpContextBase context = filterContext.HttpContext;
        HttpCookie theamCookie = context.Request.Cookies["TheamCookie"];

        if (theamCookie == null)
            context.Items["TheamFromBrowser"] = "default";
        else
        {
            if (string.IsNullOrEmpty(theamCookie.Value))
            {
                context.Items["TheamFromBrowser"] = "default";
            }
            else
                context.Items["TheamFromBrowser"] = theamCookie.Values["TheamVal"].ToString();
        }
    }
}

Answer 1

Regarding this line:

if (filterContext.HttpContext.Items["Theam"] != null)

HttpContext.Items is a request-level setting. That means you need to reload it on every HTTP request. If you are not setting HttpContext.Items["Theam"] somewhere in the request lifecycle before this piece of code is run, it will always be empty.

I am not sure that is your problem, but it would explain why the rest of your code is working when you set the variable manually.