Invitation tab does not appear in invited users accounts

Hello,

I'm using rsvp rc3 with Drupal 6.14. The selected connector is Date, and there is only one association with a DateTime field in a content type C where there are 4 other fields.

- I create a first content C with no invitations. The tab 'Invitations' does not appear in invited users accounts : OK.
- I create an invitation for this first content C (all users) and I send it. The tab 'Invitations' does not appear in invited users accounts : ?
- I create a second content C with no invitations. The tab 'Invitations' does not appear in invited users accounts : ?
- I create an invitation for this second content C (all users) and I send it. The tab 'Invitations' appears in invited users accounts, with the 2 invitations above!
- If I delete the invitation for one of the two contents C, the tab 'Invitations' disappears in invited users accounts : ?!
- and so on...

So, when there is only one invitation, the tab 'Invitation' does not appear.

Any idea ?
Thanks.