this is my code of file AllTests:
import org.junit.runner.RunWith;
import org.junit.runners.Suite;
@RunWith(Suite.class)
@Suite.SuiteClasses({
    ElementTests.class
})
public class AllTest {}
ElementTests.java
import org.junit.Test;
import pl.polsl.lab1.Model.*;
import static org.junit.Assert.*;
import org.junit.Test;
public class ElementTests {
    @Test
    public void properSymbolPlayerTest()
    {
        //given
        ElementOfBoard element = new ElementOfBoard();
        ElementOfBoard element2 = new ElementOfBoard();
        //when
        element.setSymbol(1);
        element.setSymbol(2);
        //then
        assertEquals('O', element);
        assertEquals('X', element2);
    }  
}
Please, how to solve it? I am using junit 4.11. I really have no idea what initialization error could be. Can you help me please?
My Stack trace:
org/hamcrest/SelfDescribing
java.lang.NoClassDefFoundError
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getConstructor0(Class.java:3075)
    at java.lang.Class.getConstructor(Class.java:1825)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)