Unable to login

Hello.

I use page restrict to lock the entrance to a documents page on my website. I’m registering the people myself, because I only want them to have access who booked me.

I tested it now with 3 clients. As I don’t want them to have any rights beside viewing the site, I set them all as subscriber. No one of them is able to login though.

Can anyone tell me what I’m doing wrong? Thanks in advance.

PS: As the clients click on “Log in” they are shown a totally blanc page and on the top left corner there stands “Blocked” nothing else.

http://wordpress.org/plugins/pagerestrict/