Joomla login blank page

When I try to login with the wrong credentials I get a blank page instead of getting the error message. When I click the back button on my browser and then F5 (refresh) I get the error message. I have tested this with another template and it works just fine. By the way, my template is Simplicity II. I have also try to change the error reporting to maximum in configuration but I don't get any error messages. I get only a blank page. My website is [login to view URL] (joomla 2.5) What I am asking is someone to fix this. I would like to get the error message when the wrong credentials are entered. Thank you