Error with outputDirectory tag

[omsrobert]

How can I resolve this error? I am using GWT 1.6 and maven 2.x, gwt-
maven 1.1

<build>
<!-- Compile classes into the war transient directory for hosted
mode live editing -->
<outputDirectory>${gwt.output.directory}/WEB-INF/classes</
outputDirectory>

<plugins>
<plugin>

Error - cvc-complex-type.2.4.a: Invalid content was found starting
with element 'outputDirectory'. One of '{"http://maven.apache.org/POM/
4.0.0":defaultGoal, "http://maven.apache.org/POM/4.0.0":resources,
"http://maven.
apache.org/POM/4.0.0":testResources, "http://maven.apache.org/POM/
4.0.0":directory, "http://maven.apache.org/POM/4.0.0":finalName,
"http://maven.apache.org/POM/4.0.0":filters, "http://maven.apache.org/
POM/4.0.0":
pluginManagement, "http://maven.apache.org/POM/4.0.0":plugins}' is
expected.

[Sam Brodkin]

Robert maybe it will help if you compare your pom to the my working
example from the maven gwt starter app. There I'm using the war dir
as outputDirectory but that's probably irrelevant to your problem:

http://code.google.com/p/gwt-maven2-starter-app/source/browse/web/pom.xml

Sam