BUILD FAILED messages in output when using <Ant/> tasks

Hey all.
I notice when using the <ant output="mylog.txt" .../> task if a exception or error occurs in the Ant project then the error doesn't show up in the <ant> task's output file (in this example "mylog.txt").

EG:

with ant code:

   <target name="test1">
      <ant dir="${basedir}" inheritAll="false"
         target="test2" output="${basedir}\mylog.txt">
         <property name="myparam" value="what"/>
      </ant>
   </target>
   
   <target name="test2">
      <taskdef/>
   </target>

The output is (ignore the line numbers):

   test1:
   test2:

   BUILD FAILED
   C:\work\WS\build\build.xml:4580: The following error occurred while executing this line:
   C:\work\WS\build\build.xml:4586: Only antlib URIs can be located from the URI alone,not the URI

But the contents of mylog.txt is just:

   test2:


Is there anyway to make the error show up in the output file (mylog.txt)?

Thanks!