jira logs out when i log in confluence

We have jira installed using mysql database. Besides this, we have conflence installed using its own mysql database for spaces but jira database for user delegation. When using both systems as a user, system logs the user out. For example,
while i am online at jira, if i log in confluence, automatically the jira logs me out. And then, confluence logs out respectively.

We are using both systems with evaluation license.

What may the problem be?

Thanks.