Create versioned folders using API

I try to create folders with versioning enabled on EP6.

I use the com.sapportals.wcm.repository package.

My code looks like this:

IResourceFactory resourceFactory = ResourceFactory.getInstance();

ICollection parentCollection = (ICollection)resourceFactory.getResource( getParent(), rContext);

this.resource = parentCollection.createCollection( getName(), parentCollection.getProperties());

this.resource.enableVersioning(true);

But the created folders, don't have versioning enabled. I still have to activate it manually.

What's wrong ?