RMIC ant task failing with base not supported

Question

I am running the following target in my build.xml

<target name="rmiserver">
<rmic base="../bin" classname="com.deleted.ctiv.remote.IvProvisionerResponseImpl"></rmic>
</target>

and I get the following error

[startAnt]      [exec] BUILD FAILED
[startAnt]      [exec] /home/gtaadm/gta/tomcat-5.5.20-8/webapps/taiga-2.0/project/working/EBIG_1.1/revision-1722/build.xml:44: The following error occurred while executing this line:
[startAnt]      [exec] /home/gtaadm/gta/tomcat-5.5.20-8/webapps/taiga-2.0/project/working/EBIG_1.1/revision-1722/ebig/ear/build.xml:57: The <rmic> type doesn't support the "base" attribute.

It works when I run it eclipse, but not in my automated build environment.