I hope it’s not the wrong Way to answer this Question by myself. The post from Milo has helped me defintely:
https://wordpress.stackexchange.com/a/108647/63272
I once made this otherwise:
'has_archive' => 'myproducts',
before i have allways set this to: true, because i may have not quite understand it.
If you also have troubles with this, try set this arg in your reg. cpt to: post-type-name-slug. I d’ont know what’s the difference to the default used value.