[Webtest] How to decipher error output?

[Scott Glaser]

While running the following webtest script I get the below error. Any ideas
why I'm getting the assertion failure for the invoke step indicated? Since
I'm new to webtest I don't know how to generate more informative output to
debug the problem.
 
Scott
 
<project name="SimpleTest" basedir="." default="main">
 
  <property name="webtest.home" location="/home/sglaser/util/webtest-2.1" />
  <import file="${webtest.home}/lib/taskdef.xml"/>
 
  <target name="main">
    <webtest name="myTest">
      <config
        protocol="https"
        host="login11.marketingsolutions.yahoo.com"
        port="443"
        basepath="adui" />
      <steps>
        <invoke
          description="get login page"
          url="signin/loadSignin.do" />
        <verifyTitle
          description="verify title"
          text="New Sponsored Search Login" />
      </steps>
    </webtest>
  </target>
</project>
 
main:
   [invoke] java.lang.IllegalStateException: FAILED ASSERTION
   [invoke]     at org.mozilla.javascript.Kit.codeBug(Kit.java:477)
   [invoke]     at
org.mozilla.javascript.Interpreter.increaseICodeCapasity(Interpreter.java:17
07)
   [invoke]     at
org.mozilla.javascript.Interpreter.recordJump(Interpreter.java:1529)
   [invoke]     at
org.mozilla.javascript.Interpreter.addGoto(Interpreter.java:1459)
   [invoke]     at
org.mozilla.javascript.Interpreter.visitStatement(Interpreter.java:722)
   ...

BUILD FAILED
/home/sglaser/util/webtest-2.1/doc/samples/SimpleTest.xml:7: Canoo Webtest:
R_1393.
Test failed.
Test step invoke
(/home/sglaser/util/webtest-2.1/doc/samples/SimpleTest.xml:16: )  named "get
login   page" failed with message "Step[invoke "get login page" (1/2)]:
Script error loading page executing   webtest at: invoke FAILED ASSERTION