title: The parameter regionName must be null
body: <p>I am using system.Runtime.Caching.dll for caching some values. But when i implement region i am getting error. Exception is says : "The parameter regionName must be null."  Do you have any idea about this problem.. Whay i am getting this. Or how can i add region inside .net caching method...</p>
  
  <p>my sample source code is : </p>
  
  <pre><code>            ObjectCache cache = MemoryCache.Default;
  
              policy.AbsoluteExpiration = DateTimeOffset.Now.AddSeconds(100000.0);
  
              cache.Add("xxtr", "turkish", policy, "EN");
              cache.Add("xxtr", "türkçe", policy, "TR");
              cache.Add("xxtr", "ru_turki", policy, "RU");
              cache.Add("xxru", "russia", policy, "EN");
              cache.Add("xxru", "rusça", policy, "TR");
              cache.Add("xxru", "ru_russi", policy, "RU");
  
              string df = cache.GetValues("TR", "xxtr").ToString();
  </code></pre>