- Edited
The mail problem is not the issue anymore... When using gmail it works..
yes is used a theme, but it worked a few weeks.. i really don't know what i changed that it does not work anymore... and yes is used the latest version.
But also in the admin panel sometimes it's dutch and when i click something it is English again.. I did not change anything on the admin pages with the source code... I removed the old NL.phar and uploaded the new one again. @ Synt4xError, u mentioned installing the language pack? If i put it in the i18n folder it's showing it on the admin panel.. did i missed something with installing maybe?
found a way to extract the nl.phar! now it seems like its working!! Thanks for pointing that Synt4xError!! Strange that after uploading nl.phar i could choose NL and it worked for a while..