Compilation successful, NoClassDefFoundError in ant java task

I already have many hours on the internet and have read many similar questions like this and. I've now simplified my code to a few short lines, so the problem should be obvious - but I still can't seem to solve it.

Here are my two simple classes:

package ant;
import my.package.util.exception.UtilTest;
public class Debug {
    public static void main(String[] args) {
        System.out.println(UtilTest.myTest());  
 }
}


package my.package.util.exception;
public class UtilTest {
        public static boolean myTest(){
            return true;
        }
}

      

        
        
        
      

    

I built my.package.util.jar and put it in the lib directory under the project directory. Now I ran the ant built script (see below) to build the jar for the Debug class. Built is sufficient, MANIFEST.MF:

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.9.4
Created-By: 1.8.0_20-b26 (Oracle Corporation)
Main-Class: ant.Debug
Class-Path: lib/my.package.util.jar

      

        
        
        
      

    

with an empty line at the end.

Here is the build.xml file:

<?xml version="1.0"?>
<project>   

    <path id="my.classpath">
        <fileset dir="lib/" includes="**/*.jar"/>
        <pathelement location="."/>
        <pathelement location="bin"/>
    </path>

    <target name="compile">
        <mkdir dir="build/classes"/>
        <javac includeantruntime="false" srcdir="src" destdir="build/classes" encoding="UTF-8">
            <classpath refid="my.classpath"/>
        </javac>
    </target>

    <target name="jar">
        <mkdir dir="build/jar"/>
        <jar destfile="build/jar/Debug.jar" basedir="build/classes">
            <manifest>
                <attribute name="Main-Class" value="ant.Debug"/>
                <attribute name="Class-Path" value="lib/my.package.util.jar"/>
                <!-- EDIT: to solve the issue, use value="../../lib/my.package.util.jar"/-->
            </manifest>
        </jar>
    </target>

    <target name="debug">
        <java classpath="${my.classpath}" jar="build/jar/Debug.jar" fork="true">
            <arg value="${file}"/>
        </java>
    </target>
</project>

      

        
        
        
      

    

By running ant debug "I get:

debug:
        [java] Exception in thread "main" java.lang.NoClassDefFoundError: my/package/util/exception/UtilTest
        [java]  at ant.Debug.main(Unknown Source)
        [java] Caused by: java.lang.ClassNotFoundException: my.package.util.exception.UtilTest
        [java]  at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        [java]  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        [java]  at java.security.AccessController.doPrivileged(Native Method)
        [java]  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        [java]  at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        [java]  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        [java]  at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        [java]  ... 1 more
        [java] Java Result: 1
BUILD SUCCESSFUL
Total time: 1 second

      

        
        
        
      

    

Who can help?: -/

Any hints are appreciated!