Seefaring doesn't work on nightly Build

Hi,

1. I load the Widelands map: The big lake into the editor.
2. I place the first player (Marius) on the coordinates 69,74.
3. I mark Port 1 on the coordinates 82,66
4. I mark Port 2 on the coordinates 66,95
5. Now I save the map as The big lake.

6. I start a new game (The big lake).
   Now I notice, that now there are a lot of marks for building a Port, and not only the two places I marked.

7. I expand my territory to the two points I marked and build the Ports.
8. After building the Ports, I destroy the military buildings and the roads, so there is not longer a connection between the heeadquarter and the Ports.
9. I now build a Shipyard, and also build a woodcutter near Port 1 and a Sentry near Port 2.
10. From build 6561 I noticed that no ships were build. First I thought I had a bad spot were I build the Shipyard.
    But were I build the Shipyard, I always got the hoover text: no use for ships on this map.