How to test invoked private method to throw ArgumentNullException?

I want to test an invoked private method from a certain class. It should throw ArgumentNullException. But unfortunatley I get this message:

Expected: <System.ArgumentNullException> But was: null

[TestCaseSource("InvalidValidInput")]
    public void T2(EMP exmpl,List<string> wrongIn)
    {
        ClassConverter cc = new ClassConverter();
        Type ccType = cc.GetType();
        MethodInfo converter = ccType.GetMethod("Convert", BindingFlags.NonPublic | BindingFlags.Instance);

        var tooManyInp = Assert.Throws<ArgumentNullException>(() => converter.Invoke(cc, new object[]
            {
                exmpl,
                wrongIn
            }));

        Assert.IsInstanceOf<ArgumentNullException>(tooManyInp.InnerException);
    }
}