Outlook E-mail Problem !! Help!!!

[EvgeniX]

I use gmail and set it to get all email every 15 min.

Example:

When i get email at nite i get message that i have new email but when i try to read it my inbox empty??

Who and why delete all my email after some minutes.

Even if I already read email I close Outlook and in 1 hour I open it again and my Inbox empty.

Can some one help?? Why it delete email?? I was looking in settings but did not found?

Please Help