Vaadin 7 & Jmeter - RPC call to v.v received for connector 73 but no such c

I’m trying to use Jmeter to load test my web application based on Vaadin 7.
Following this doc ( and others, I first disable the xsrf-protection, and set an Id ( with setId() ) to all the abstract components.
Now I can record and launch some tests with defined variables in the UIDL request (my FieldComponents).
But a test always fails with this error :
nov. 04, 2013 3:08:54 PM com.vaadin.server.communication.ServerRpcHandler parseInvocation
WARNING: RPC call to v.v received for connector 73 but no such connector could be found. Resynchronizing client.

It seems like the component’s id in the UIDL changes everytime a new record is saved. (even if I set every component’s id, well I think so).

I’ll try to explain it.
The test is basically as such:

  1. log into the application
  2. display a view with a table ( with JPAContainer of my beans as DataSource)
  3. click a button to open a new window and create a new bean
  4. enter bean details and open a new Window to add a BeanItem to this bean
  5. fill the beanItem and save it (multiple BeanItems could be added but I just add one)
  6. save the bean.

The test always fails when the beanItem is saved (step 5)

Here’s what I figured out.
Where I record the test for the first time (the table is empty, as the container has no data) the request when saving the beanItem is:

Works for the record, no error in the server, the database is updated but I can’t launch the test a second time (RPC call to v.v received for connector 73 but no such connector could be found) UNLESS I remove the bean (then I can run the test once).

So I record the same test with the container having the 1st bean and I got this request:

same one, except some ids have been increased by 70 (73 → 143 and 77 → 147), ids that I suggest are the Windows one.
I can’t launch the test (Warning on connector 143) unless I clear the record and leave only one bean in the container.

If I leave the two beans in the container and record the same test again, the request is now :
Here again ids increased by 70.

Why +70 ? and why not the id I set ? What did I miss ?
Any help will be apreciate