You also need to have the associated ResourceLink in the context.xml for your app. For example, if your webapp is named foo, there should be a file called conf/Catalina/localhost/foo.xml
with a
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Context>
<Context antiJARLocking="true">
<ResourceLink name="property"
type="classname"
global="propertyNameInGlobalNamingResources" />
...
</Context>
If you include a META-INF/context.xml
with these links in your war file, tomcat will copy it out to the conf/Catalina/localhost/foo.xml
the first time the app is deployed (though not any time after that as you are intended to make changes there and be able to deploy again without clobbering customization)