Cache Never Expiried

Question

Hi All,
This source what i have used to create cache object.Also i have checked if "AppCache_Caption" cache object is available or not.

 if (HttpRuntime.Cache["AppCache_Caption"] == null){HttpRuntime.Cache.Insert("AppCache_Caption", dicCache, null,System.Web.Caching.Cache.NoAbsoluteExpiration,System.Web.Caching.Cache.NoSlidingExpiration,System.Web.Caching.CacheItemPriority.Normal,null);}
Right now i have checked and created my login page page_load event. It will create cache object every time me access the login page.

What are the conditions wrong my source?
My expectation, cache object creates only one time.It will not create everytime.
Please help me
Thanks in advance
Rameshkumar.T