Faulty float base ai operation

I have come across a problem with a new float base I made. I have made float bases before and they are fairly simple: a 1 foot wide concrete runway (invisible in water at that width) and 1 foot wide concrete paths to parking spots at docks (though float planes don't seem to mind parking at "ramp" parking spots either). I have used for testing an ai plane that has functioned ok in all other instances. I have opened the float base in afcad and run the check for faults, and there are none. I have checked the hold shorts are the right way around and they are. The ai plane lands and taxies to the parking ok. When it comes to the time for takeoff it does not taxi and take off, it just vanishes from the parking spot. I took that as an indication that the next task (to take off) is impossible, as when a plane lands and is on the runway and the next task is to park and there is no parking spot available (either literally, or not one that is the right size) it vanishes. I made the runway longer, even though I knew that the ai plane could take off in the runway length available. Same story. Any ideas?

I have found the problem, and it was, inevitably, human error. The taxiways MUST be surfaced with concrete, and that includes the runway taxiway, even though the runway taxiway and the runway itself are "called" water. I had carelessly made the runway taxiway as water surfaced. Duh