Hi jrf,
thanks for your answer!
I tried sooo much, but nothing worked. Next I´ll check if a plugin is causing the problem.
My solution for now is:
1.) uncheck force rewrites
2.) replace the <title> with:
<title><?php wp_title('true','right'); ?> | <?php bloginfo('name'); ?></title>
Even the codes in the http://codex.wordpress.org/Function_Reference/wp_title did not work here :-/
Is the code:
<title><?php wp_title('true','right'); ?> | <?php bloginfo('name'); ?></title>
all right? Are there any negative side effects to the yoast plugin?
Thanks in advance!
manuel