Configuration class Yaml

I've been trying to make a simple yaml file work. I think I might have gotten it wrong.

I tried this:

Code:

        Configuration myConfig = new Configuration(new File("Test.yml"));

        myConfig.setProperty("test.foobar", "Hello World");
        myConfig.save();

But I always get a NullPointerException from save() no matter what I do.
Can anyone lead me in the right direction please.

SOLVED: The file needed to use a directory, since the save(); method checks for the parentFile. file.getParentFile().mkDir(). Without checking if there actually is a parentfile present. So new File("Config/Test.yml") works.