[antlr-interest] Is the -profile option suppose to work with tree grammars?

[The Researcher]

>From http://www.antlr.org/download  examples-v3.tar.gz
java/simplecTreeParser I tried

java org.antlr.Tool -profile SiimpleC.g SimpleCWalker.g
javac *.java

and received error

org.antlr.runtime.debug.Profiler can not be applied to (SimpleCWalker)

Is the error correct, did I miss something, or is this a bug?

I did get the profile option to work with the cminus example.

Thanks, Eric