Can't show boat data

[mondello]

Win XP - Firefox 5.0.1 with Httpfox - VRTool 1.97f

Trying to import data from FF cache, I notice that:
1. SCAN FIREFOX CACHE works. I can see the required data list.
Here the problem is that not only the newest but even the oldest data are shown.

2. IMPORT SELECTED FILES doesn't work.
The first time, all goes well: the message "Imported x file(s)" appears, the boat positions are refreshed and the points on their tracks are added.
The next times, the message "Imported x file(s)" appears but the boat positions are not refreshed and the points on their tracks are not added.

Does anyone know how:
1. Avoid that the oldest data are included when scanning the FF cache
2. Refresh the boat positions and their tracks