Armando,
A little more information to help you fix this particular "feature" of the FLogger.
If I start a new log having selected a flight and aircraft, I often find I cannot select a new flight and aircraft to associate with the new log...
I'm doing a flight now, and because I clicked the "New Log" button (started the engine then realised I hadn't set up FSP for the leg, so stoped the engine and made a new log in the FLogger) I cannot choose an aircraft and flight from the Timetable "tab". Thankfully, I'm only flying a VFR WT leg, so the not being able to select an aircraft or flight isn't a problem...
I'll try again after I land this leg (selecting aircraft and flight *before* clicking "new log" this time) to see if I can get a repeatable workaround.