I guess you have to be open to the possibility to even have a genuine "dream communication".
Until a few years ago, I thought dreams don't mean anything, and I still would say that often enough they probably only mean that you've eaten the wrong things too late in the evening. But when my sister - who is not esoterically inclined but more open to possibilities than I am - told me about a dream she'd had where a deceased relative seemed to have announced her being reborn in her child, I pricked up my ears, because I had read about many dreams like that in Ian Stevenson's cases. And later of course, my sister's child started showing behaviour and making remarks that reminded me of the deceased, or could be very well interpreted as being related to memories of the special relationship I'd had with the deceased, which led to some amazement and re-evaluation of things for me, to say the least.
The only time I personally dreamt about a dead relative was a few days after my grandfather had died. This had been many years earlier, when I was still a lot more sceptical. I had been living upstairs from him for some years and in the dream I could hear his characteristic way of coming up the stairs to my floor. I wasn't afraid at all, although after a short time I was like "well, that isn't right..." Then, the door opened and my grandfather entered the room, looking as always but seeming somewhat confused. Continuing my thought, I was like "this can't be, because you're dead".
That's where it got weird, because instead of me getting creeped out, it was like just the opposite was going on. My (dream-)grandfather looked at me as if he was seeing a ghost. He literally shrank back from me in what seemed to be real terror. And then I woke up.
As far as I know (because we do have dreams every night which we don't remember or forget soon after waking up) I've had no other dream either about him before or after that, or about any other deceased relative, not even the one my sister dreamt of (although I would have had reason enough for that).
I think that might be because I'm still not open enough for that kind of thing. If you can believe that.