What are the possible causes of com.sun.deploy.net.JARSigningException : Could not verify signing in resource; while using a JNLP based program?

Question

This is some of the stack trace for the exception :

com.sun.deploy.net.JARSigningException: Could not verify signing in resource: .jar at com.sun.javaws.security.SigningInfo.checkSigning(Unknown Source) at com.sun.javaws.LaunchDownload.checkSignedResourcesHelper(Unknown Source)

We ourselves are signing all the jars referred in the JNLP deployment XML with a valid certificate (root CA authorized), and worst is it seems to have broken after some code changes to one of the java classes were added.

Thanks in advance.