Ninject MVC bind constructor arguments to HttpContext.Current.Session

Foo.cs

public class Foo : IFoo
{
    string _applicationName;
    string _currentUserName;  

    public Foo(string applicationName, string currentUserName)
    {
        _applicationName = applicationName;
        _currentUserName = currentUserName;
    }

    public void Bar()
    {

    }
}

IFoo.cs

public interface IFoo
{
    void Bar();
}

NinjectMVC3.cs

public static class NinjectMVC3
{
    //Other bootstrapper methods removed to be more concise

    private static void RegisterServices(IKernel kernel)
    {
        kernel.Bind<IFoo>().To<Foo>()
              .WithConstructorArgument("applicationName", "value1")
              .WithConstructorArgument("currentUserName", x => GetSessionValue("UserName"));
    }

    static string GetSessionValue(string key)
    {
        if (HttpContext.Current == null) return "";
        var httpSessionStateBase = new HttpContextWrapper(HttpContext.Current).Session;
        if (httpSessionStateBase != null && httpSessionStateBase[key] != null)
            return httpSessionStateBase[key].ToString();
        return "";
    }
}

I tried using this .It works fine for the first call during that request However in subsequent call the session values are returned Null.