I've got a working hello-world like webpart for my SPS3.0

I can compile, pack and deploy it using VS2008, makecab.exe and stsadm. So I know the theory of deploying sharepoint webparts.

My problem:

After I inserted an additional .webpart file, an elements.xml and a feature.xml to deploy the .webpart file and get knowledge about adding features to my webpart, the deployed webpart is missing its safe control entry in the web.config. But the dll can be found in the gac and my features are also deployed to the right folders. I didn't change anything in my manifest.xml especially not in it's -tag, because it definitely worked before i added my additional feature files.

Can anybody help me? Should i provide you some code snippets?

Thanks Stefan