After that opened my xxx.ear in the winzip and replaced the said the new xxx.jar with the one that was already present.
My guess, is that this seems to be packaging issue. Try the following command out and post the output of the same:
jar -tf myOld.ear
jar -tf myNew.ear
Both these commands will display the contents of the ear files. Try comparing both the outputs, you might get a clue of whats gone wrong.
Thank you Jaikiran
I figured it out....the problem was in packaging. one of the classes had an error relating to an import of a class which was to be found in another jar. I did not think that would cause any trouble in the creation of the new jar since once inside the ear the jar should be able to reference the correct classs. Apparantely this was causing trouble. Once I imported the classes from the other jar and then exported my jar once more, it worked fine.