websphere procompile jsp , it has errors, but build successful

Env: websphere 6.0

Problem: After compile jsps
The result is:

wsJspC JSPG0151I: Return code: 1
wsJspC
wsJspC JSPG0169I: The Batch Compiler exited with errors.
wsJspC Java Result: 1

BUILD SUCCESSFUL

the build should be failed, but it doesn't. Also the
<taskdef name="wsjspc"
classpath="${websphere_lib_directory}/wsanttasks.jar;${websphere_lib_directory}/wsprofile.jar;"
classname="com.ibm.websphere.ant.tasks.JspC" />

the wsjspc doesn't have Failonerror option.

Please give me help, let me know how to make the build failed, if there is compile errors.

Thanks