Creating a folder with DFC (Documentum)

I'm facing a strange problem. All I want is to create a new folder with the DFC. But when I execute the code (JUnit or inside the Application) no folder is created and surprisingly no exception is thrown. So I guess the error is somewhere else.

This is my code:

public void createNewFolder(String sFolderName, String sParentId)
{
    IDfSession session = null;
    try 
    {
        session = getSession();     
        IDfFolder newFolder = (IDfFolder) session.newObject("dm_folder");
        newFolder.setObjectName(sFolderName);
        newFolder.link(sParentId);
        newFolder.save();
        String sDump = newFolder.dump();

        System.out.println("Folder ["+sFolderName+"] saved.");
        System.out.println("Folder has id ["+newFolder.getId("r_object_id")+"]");
    }
    catch (DfException e) 
    {
        e.printStackTrace();
    }
    finally
    {
        m_sessionManager.release(session);
    }

I'm getting a sysobject id in return, but when I'm trying to fetch it with a dql statement then I cannot find it.

I tried to execute a dql create query alternatively which creates the folder. This does not work with JUnit or in the running Application, but when I execute it manually it simply works.

This is my getSession() method

private IDfSession getSession()
{
    try 
    {
        if (m_sessionManager == null)
        {
                return establishConnection();
        }
        else
        {
            return m_sessionManager.getSession(m_sRepository);
        }
    } 
    catch (DfException e) 
    {
        e.printStackTrace();
    }
    return null;
}

Any ideas on that?

Thanks to the comments of unicron. This actually let me fix the problem. In my establishConnection() method, which I did not post in the question, I actually used beginTransaction(). Removing that fixed the problem and everything worked fine.

public IDfSession establishConnection(String sUserName, String sPassword, String sRepository) throws DfException 
{
    System.out.println("Login");
    IDfClientX clientX = new DfClientX();

    IDfClient localClient = clientX.getLocalClient();
    IDfSessionManager sessionManager = localClient.newSessionManager();
    IDfLoginInfo loginInfo = new DfLoginInfo();
    loginInfo.setUser(sUserName);
    loginInfo.setPassword(sPassword);
    sessionManager.setIdentity(sRepository, loginInfo);

// THIS IS THE EVIL LINE !
    sessionManager.beginTransaction();

    System.out.println("sessionmanager ist geladen");
    IDfSession session = sessionManager.getSession(sRepository);
    m_sUserName = sUserName;
    m_sRepository = sRepository;
    m_sessionManager = sessionManager;

    return session;
}