Pl. make sure that you expanded the downloaded samples zip file according to the instructions specified at
http://java.sun.com/javaee/reference/code/.
"After downloading the samples bundle, install it under <sdk-install-root>/samples so that it looks like <sdk-install-root>/samples/j2ee14. Remember to update <sdk-install-root>/samples/j2ee14/common.properties before you start working with samples. Refer to <sdk-install-root>/samples/j2ee14/index.html for details."
Important thing is to make sure that the samples are expanded under <glassfish-install-root>/samples because the location of common-ant.xml is computed relative to the current location where the ant target is executed.
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