.NET ZipFile for solution packaging

Hi,

we unzip an exported solution with the ZipFile class in .NET (C#). Aftwerwards we zip it again with the same class. If we try to import this solution into Dynamics 2011 it fails because of some invalid attribute/property.

If on the otherhand we zip the files with 7Zip oder the Windows function, the solution can be imported successfully.

Does anybody know how to use the ZipFile class in .NET to create a valid zip-file for Dynamics 2011?