网站上的iFrame不保存cookie

I am new here and not a native English speaker. So please bear with me. :)

I made an website for a game called EVE Online. This website is for my alliance. This was my first website I ever made without the help of editors (except notepad++), so the code is not perfect but I guess it works (almost). :p

I have an navigation bar on the left side. From this bar a user can select the different pages we have. (Forum, Timerboard, Links, other stuff). When a user Logs in into the Forum or the Timerboard, the login will only be saved for maximum a few hours.

When I for example log in to the Forum and visit it the other day I am not logged in anymore, even if I tick the "stay logged in" box.

The website uses iFrames to keep the navbar on the left side. Just have a look here: http://www.vega-home.de

Would be nice if I can get some answers. All I found using Google Search was a problem with Cookies and old versions of IE. But that problem we have happens in all browsers.

Thank you for any help I can get!

Best Regards, Frank. :)

After deleting old cookies problem is solved. Thanks anyway. :)