JBPM process creating issue

I have a jboss seam and JBPM integrated application that is working fine. I put my own servlet in it, but through that servlet when i try to create a JBPM process i am facing exception mentioned below.

Blockquote

org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [org.jbpm.graph.exe.Token#2763785]

Here is code what i am doing,

 String processName = "adhocIssue" ;
      StandardWorkflow jbpm =StandardWorkflow.instance() ;
      System.out.println("nothing.........");
      // StandardWorkflow.SeamBusinessProcess processContext = jbpm.clearSeamBusinessProcess();

      //Exception occurring at this line. 
      ProcessInstance process = jbpm.createProcess(processName);
      jbpm.addVariable(process, "memberId", 326543);
      jbpm.addVariable(process, "adhocIssueTitle","adhocIssueTitle");
      process.getRootToken().addComment(new Comment("262", "This is adhoc issue"));
      return null;

I am not uploading configuration files as JBPM is working perfectly with JBossSeam and JSF application. But when i am starting process through my own servlet i am facing this problem.