Rewriting Custom Post Types

I changed the permalink structure to “/%postname%” in the permalink settings.

my custom post type permalink parameter is:
‘rewrite’ => array(“slug” => $this->mpermalink, ‘with_front’ => true)

but it then gives a 404

if i leave it to the old settings it works via ?whatever=mypost
so it does not work with /whatever/mypost

how can i change it so this works?