Package namespace not available

Hey guys, i developed a own L5 package. I developed it on a fresh L5 installation and it works perfectly. I added the package to my github and want to install it on another project via composer. The cloning of the repository is succesfull and the files are at the correct place under vendor/myname/project.

I added the PackageServiceProvider:class to my config/app.php. But L5 cant find the namespace. only if i define the package namespace in root composer.json my package works.

Does anyone has kind of an idea?

Best regards