Checking if class is child of class

I am loading classes via ClassLoader:

Class<?> clazz = urlClassLoader.loadClass(name.substring(0, name.length() - 6).replaceAll("/", "."));
System.out.println(clazz);
System.out.println(clazz.isInstance(SkillCast.class));
System.out.println(SkillCast.class.isInstance(clazz));
System.out.println(SkillCast.class.isAssignableFrom(clazz));
System.out.println(clazz.isAssignableFrom(SkillCast.class));

This is my structure:

public class SkillFireball extends SkillCast implements ISkillThrown
public abstract class SkillCast extends Skill

And prints are:

class skills.SkillFireball
false
false
false
false

What I am sure of is that clazz is SkillFireball and I can print field/method names.

How can I check if clazz is child of SkillCast?