Rebuilding UI

System

When I run iwperl /bin/make_toolkit.ipl from the appropriate customer_src directory, I get a message I haven't seen before:

java.lang.InstantiationException: org.apache.tools.ant.Main
at java.lang.Class.newInstance0(Class.java:293)
at java.lang.Class.newInstance(Class.java:261)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:195)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:55)

I've restarted iwwebd and other services but nothing.

What gives?

TS6.5 SP2/Win2k3