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Thank you for your reply.

Guess what? I got it working!!!

I was using Eclipse to build my Web application and that was the problem.

I didn't know that I shouldn't be putting files directly into the

WEB-INF/classes directory when building Web applications using Eclipse( and other IDEs).

I put the properties file in the WEB-INF/src directory

(Eclipse automatically copies the properties file in the WEB-INF/classes directory) and everything worked perfectly.