A man owns a horse which lives in a field near a school bus stop, so every day the children stop by the gate and feed the horses bits of chocolate, sweets, cakes, etc. Naturally the horses get fatter and start to look pretty unhealthy.
The owner puts out a sign saying DON’T FEED THE HORSE. No affect. The children still do.
Another sign PLEASE DON’T FEED THE HORSE. Still no affect.
Then a wise friend suggested a new sign I ONLY EAT APPLES AND CARROTS.
You can guess the result: happier, healthier horse and the children still able to feed it.
Morale of the story: convey what you WANT not what you DON’T want to those you want to influence.