okay removing 'generated' from the property element in detail.hbm.xml done the trick. But these XML files were created by MyEclipse itself and this 'generated' attribute was also added by MyEclipse. So i am bit confused why this error was comming up? I also want to know that i have wordId in detail.hbm.xml of type String. I want to make it auto increment so that whenever an insert is made in the table it generates the key itself. How to solve this? View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4233631#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...