Problems with ANT: "java_home"

I’m trying to build the spark pluging following the instructions in “how-to-build.txt” attached below, but when I run “ant jar” in the command line (I’m not using Eclipse), it says

Perhaps JAVA_HOME does not point to the JDK

It is currently set to “C:\Program Files\Java\jre1.6.0_07”

However if I run “set JAVA_HOME” in the command line (this is windows XP) I get:

JAVA_HOME = C:\Program Files\Java\jdk1.6.0_06\bin
how-to-build.txt (715 Bytes)

So you can just tell ANT where javac.exe using the “exectutable” attribute: