HttpContext.Current.Session null on page rendering when im adding CustomUrlAuthorizationModule tag to web.config

Question

Dear, I'm facing a problem with HttpContext.Current.Session when I'm adding CustomUrlAuthorizationModule tag to web.config. Every time i'm adding the above tag to my web.config, HttpContext.Current.Session is null every time the page is rendered.

PS: i'm using HttpContext.Current.Session from SQLSiteMapProvider class from BuiltSiteMap() function.

Any suggestions? Thank you in advanced, Regards, Jad