missing translation… can't find the .po field for it…

Hello,

I’m developping a site un french language with restricted access to a page.
When people (unlogged) click on the link to the page, simple membership works perfectly and delivers a ‘deny’ message instead of the page. I cant’ the the way to translate this deny message.

Please see hereunder the screen capture :
https://www.dropbox.com/s/dloyllf9pl51e5h/Capture%20d%27%C3%A9cran%202015-01-21%2009.19.44.png?dl=0

Can you help me ??

Xavier

https://wordpress.org/plugins/simple-membership/