LINDA will not work at some occasions

I try to use LINDA in FSX. I start the LINDA application and after that FSX. Then I load an aircraft which I have configured in LINDA. I see a window telling me that LINDA is ready. And sometimes things work as expected. The buttons I have configured works as they should. But many time LINDA isn't really active since no configured buttons work. This is often the case when I start FSX the first time. If I restart LINDA it seem to work but this is very awkward and I suspect should not be needed if LINDA works as it should.