Running JMockit with cpsuite - testing

Question

We are having a problem when running unit tests using CPsuite and JMockit.
The tests run fine when executed in Eclipse, but if we use our Ant script to run all the tests (see script at the end of this question), we get the following exception:
Testcase: initializationError took 0 sec
Caused an ERROR
(class: mockit/internal/startup/JDK6AgentLoader, method: getVirtualMachineImplementationFromEmbeddedOnes signature: ()Lcom/sun/tools/attach/VirtualMachine;) Wrong return type in function
java.lang.VerifyError: (class: mockit/internal/startup/JDK6AgentLoader, method: getVirtualMachineImplementationFromEmbeddedOnes signature: ()Lcom/sun/tools/attach/VirtualMachine;) Wrong return type in function
at mockit.internal.startup.AgentInitialization.initializeAccordingToJDKVersion(AgentInitialization.java:21)
at mockit.internal.startup.Startup.verifyInitialization(Startup.java:86)
at mockit.Invocations.<clinit>(Invocations.java:22)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
This only happens on Ant, and only if there is a class that uses JMockit in the CPSuite set.
Anyone know why are we getting this error?
The Ant Script:
<project name="chughtai.junit" default="run" basedir=".">
<taskdef resource="net/sf/antcontrib/antlib.xml"/>
<!-- https://junit-anttask.dev.java.net/ -->
<!--
<taskdef name="junit2" classname="com.sun.ant.junit.JUnitTask">
<classpath>
<pathelement path="lib/junit-anttask.jar" />
<pathelement path="lib/junit-4.4.jar" />
</classpath>
</taskdef>
-->
<property environment="env"/>
<property file="junit.build.properties"/>
<filelist id="third-party_jars" dir="lib">
<file name="${ext.classpath}/bin/lib/j2ee.jar"/>
</filelist>
<path id="project.path">
<pathelement path="${env.JAVA_HOME}/lib/tools.jar"/>
<pathelement location="classes/"/>
<fileset dir="lib">
<include name="**/*.jar"/>
<include name="**/*.properties"/>
</fileset>
<dirset dir="${build.dir}">
<include name="apps/**/classes"/>
<exclude name="apps/**/*Test*"/>
</dirset>
<pathelement location="${basedir}/junittestcases"/>
<filelist refid="third-party_jars"/>
<pathelement path="${ext.classpath}"/>
<pathelement location="${ext.classpath}/WEB-INF/classes"/>
</path>
<target name="init">
<mkdir dir="${prd.junit.test.report.dir}" />
<mkdir dir="${prd.junit.test.report.dir}/html" />
</target>
<!-- default target -->
<target name="run" depends="init">
<property name="myclasspath" refid="project.path"/>
<property name="java.class.path" refid="project.path"/>
<echo message="***Junit Controller Application***"/>
<echo message="basedir is ${basedir}"/>
<!--<echo message="${myclasspath}" />-->
<junit dir="${basedir}/junittestcases/" printsummary="yes" haltonfailure="no" fork="no" forkmode="once" reloading="false" maxmemory="1024m">
<jvmarg value="-Xms768M"/>
<jvmarg value="-Xmx1024M"/>
<jvmarg value="-XX:MaxPermSize=256M"/>
<sysproperty key="tests" value="${tests}"/>
<sysproperty key="java.class.path" value="${myclasspath}"/>
<formatter type="plain" usefile="true" extension=".txt" />
<formatter type="xml" />
<classpath refid="project.path"/>
<test name="${use.testcase}" haltonfailure="no" fork="false" todir="${prd.junit.test.report.dir}" if="use.testcase">
<formatter type="xml" />
</test>
</junit>
<!-- Generate the Unit Test reports -->
<junitreport todir="${prd.junit.test.report.dir}">
<fileset dir="${prd.junit.test.report.dir}">
<include name="*.xml" />
</fileset>
<report todir="${prd.junit.test.report.dir}/html" styledir="${xsl.templates}" format="frames">
<param name="build.number" expression="${app.build}" />
<param name="application.name" expression="${app.name}" />
</report>
</junitreport>
</target>
<target name="emma.report" depends ="" description="Creates 3 EMMA report formats based on the coverage data gathered.">
<if>
<available file="coverage.ec" />
<then>
<move file="coverage.ec" tofile="${coverage.dir}/junits.ec" overwrite="true"/>
</then>
</if>
<emma>
<report sourcepath="src" sort="+block,+name,+method,+class" metrics="method:70,block:80,line:80,class:100">
<!-- collect all EMMA data dumps (metadata and runtime)
[this can be done via nested <fileset> fileset elements
or <file> elements pointing to a single file]:
-->
<fileset dir="${coverage.dir}">
<include name="*.em" />
<include name="*.ec" />
</fileset>
<!-- for every type of report desired, configure a nested
element; various report parameters
can be inherited from the parent <report>
and individually overridden for each report type:
-->
<txt outfile="${coverage.dir}/coverage.txt" depth="package" columns="class,method,block,line,name" />
<xml outfile="${coverage.dir}/coverage.xml" depth="package" />
<html outfile="${coverage.dir}/coverage.html" depth="method" columns="name,class,method,block,line" />
</report>
</emma>
</target>
<target name="clean">
<delete file="${coverage.dir}/coverage.*" />
</target>
</project>