Your question is quite confusing. I think you need to use the right terms.
Note that, the ear which will have both the jar and the war file will have a version which would be 1.4 in your case. You can find this from the application.xml file.
So, when you are upgrading, the JEE version will be 5 or 6 - so your ear will be like 5 or 6 - lets say 5. This would mean you can use EJB 3.0 and I think servlet
will continue to be 2.5
So, when you deploy a JEE 5 application, you can continue to use ejb 2.0 as the severs generally support older versions.
What is the error you are getting? what is the server you are deploying against?