Maven Compiler Plugin Fork Option Not Working

I have a maven pom file with the following compiler-plugin:

        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.0.2</version>
            <configuration>
                <executable>${path_to_JDK6}</executable>
                <fork>true</fork>
                <compilerVerison>1.6</compilerVerison>

                <source>1.6</source>
                <target>1.6</target>
            </configuration>
        </plugin>

My system's JAVA_HOME is set to a 1.5 JDK. When I run mvn package, maven throws the following error message:

Failure executin开发者_如何转开发g javac, but could not parse the error: 
javac: invalid target release: 1.6
Usage: javac <options> <source files>

Does anyone have any ideas about why Maven is using the 1.5 JDK instead of forking to the 1.6 executable? Is there any debugging option that I could use? Are the fork and executable options broken in Maven 2?

Note: My system admin would not allow me to change the value of JAVA_HOME and some of my new libraries are written for java 6. So I would like to find a workaround to make maven compile with JDK 1.6.

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My ${path_to_JDK6} variable only included the path to the folder containing the JDK. It did not include the /bin/javac. When I added /bin/javac, the 1.6 compiler was invoked.