All async unit tests timeout

I am trying to run FlexUnit tests through Ant in a very simplified version of the sampleCLIProject. The tests pass when I compile through Flash Builder and timeout when I run them through Ant on Windows. This timeout problem only occurs in the case of async tests. When I run them through Ant on Mac OS X, Ant is unable to receive data back from Flash Player.

Here's the main application that runs the tests:

TestRunner.mxml

<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"                                        xmlns:flexUnitUIRunner="http://www.adobe.com/2009/flexUnitUIRunner"                                        layout="absolute"                                        creationComplete="runTests();"><mx:Script>                    <![CDATA[                              import org.flexunit.demo.EchoPanelTest;                              import org.flexunit.listeners.CIListener;                              import org.flexunit.listeners.UIListener;                              import org.flexunit.runner.FlexUnitCore;                                public function runTests() : void{                                        var core : FlexUnitCore = new FlexUnitCore();                                        core.addListener(new UIListener(uiListener));                                        core.addListener(new CIListener());                                          core.run(EchoPanelTest);                              }                    ]]></mx:Script><flexUnitUIRunner:TestRunnerBase id="uiListener" width="100%" height="100%"/></mx:Application>

Here's the Ant build file:

build.xml

<?xml version="1.0" encoding="UTF-8"?><project name="Main Build File"         default="run"><property file="build.properties" /><taskdef resource="flexTasks.tasks"                   classpath="${TASK_DIR}/flexTasks.jar" /><taskdef resource="flexUnitTasks.tasks">  <classpath>  <fileset dir="/Users/ohassan/Downloads/flexunit 2">  <include name="flexUnitTasks*.jar" />  </fileset>  </classpath></taskdef><target name="compile">  <mxmlc file="${SRC_DIR}/TestRunner.mxml"                           output="${BIN_DIR}/Main.swf">  <library-path dir="${LIB_DIR}"                                            append="true">  <include name="*.swc" />  </library-path>  <compiler.verbose-stacktraces>true</compiler.verbose-stacktraces>  <compiler.headless-server>true</compiler.headless-server>  </mxmlc></target><target name="run"                  depends="compile">  <flexunit swf="${BIN_DIR}/Main.swf"                              timeout="5000"                              toDir="${basedir}/reports"                              haltonfailure="false"                              verbose="true"                              localTrusted="false"                              command="${FLASH_PLAYER}" /></target></project>