Simplenews logs out when sending test newsletter I am trying to send a test newsletter through simplenews and it logs me out from my website everytime I hit the send button. I am logged in as admin. I have successfully sent test newsletters before and I dont think it is a permissions issue since I have necessary permissions.
The only thing I changed was install simplenews related modules like simplenews-statistics,etc. I also copied the .tpl.php files from simplenews's module folder to my theme folder. 

What could be the problem?
I found out that the problem occurs when I use custom .tpl.php templates. I deleted the statistics module and .tpl.php files from my theme's folder. So, I am using the default .tpl.php files provided by Simplenews and it works. 

Now, I need to figure out why I can't use custom template files.