What I am going to narrate is not my own experience, but my late maternal grandfather's (nanaji). My grandfather had died when I was just 11 years old.
My grandfather was a guard in Indian Railway; he used to live in a bungalow at Kharagpur town which is located at West Bengal, India.
The incident happened when he was just 25 (don't remember his exact age.)
My grandfather and his friends decided to make a Planchette.
They were 5 friends (sorry I don't remember their names) but that day 1 friend was out for some work so all 4 friends decided to do the Planchette but only 1 friend was not serious about it and started making fun of it, he joined just for fun.
So everything was arranged, Planchette board, candles, the lights were put off and all closed their eyes everybody was told to remember the person who is dead but that friend do not bother about what was said, the process was started but he instead of remembering the dead person he thought of the 5th friend who wasn't there and after few minutes strong wind started and all the candles put out,
Then suddenly a shadow figure appeared and slowly it took the shape and everybody was surprised to see their friend. My grandfather asked when you came. Please come and sit with us, I am going to put on the lights. His friend replied no need to put on the lights and I have not come to join you, please tell me why did you call me? My grandfather was surprised because he didn't call him. His 5th friend again asked why you called me. You know I had a bad incident because of you people, after saying that he disappeared and everything was changed back to normal, the wind stopped and the lights were put on.
After half an hour they all got the news that their 5th friend met with an road accident and died on spot. Then the friend who was culprit burst out of tears and cried, he apologized and told that he was remembering him during the Planchette. All were shocked to hear that, my grandfather told that never think of any alive person during the Planchette because the spirit really comes during the process if the person is alive he/she will die.