Error during the workflow scheme association on Oracle 8: LocalTransaction rolled-back due to setRollbackOnly

Hi,
When I wanted to select a workflow scheme to a specific project, i had this error page (see attached):

Cause:
javax.servlet.ServletException: LocalTransaction rolled-back due to setRollbackOnly

Stack Trace: [hide]

javax.servlet.ServletException: LocalTransaction rolled-back due to setRollbackOnly
at com.ibm.ws.webcontainer.webapp.WebAppTransactionCollaborator.postInvoke(WebAppTransactionCollaborator.java:267)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java:794)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:201)
at com.ibm.ws.webcontainer.srt.WebAppInvoker.doForward(WebAppInvoker.java:125)
at com.ibm.ws.webcontainer.srt.WebAppInvoker.handleInvocationHook(WebAppInvoker.java:286)
at com.ibm.ws.webcontainer.cache.invocation.CachedInvocation.handleInvocation(CachedInvocation.java:71)
at com.ibm.ws.webcontainer.cache.invocation.CacheableInvocationContext.invoke(CacheableInvocationContext.java:116)
at com.ibm.ws.webcontainer.srp.ServletRequestProcessor.dispatchByURI(ServletRequestProcessor.java:186)
at com.ibm.ws.webcontainer.oselistener.OSEListenerDispatcher.service(OSEListener.java:334)
at com.ibm.ws.webcontainer.http.HttpConnection.handleRequest(HttpConnection.java:56)
at com.ibm.ws.http.HttpConnection.readAndHandleRequest(HttpConnection.java:652)
at com.ibm.ws.http.HttpConnection.run(HttpConnection.java:458)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:912)
Thanks for your answer.