Now he knows

"...I know why there is a limit on the stone!" The stone flashed.
Jon paused for a moment and started up again.
"The stone used to have no limits but a magician made a wish that made limits for the stone."
"The wish was, "I wish my people (Incans) cannot reverse the wishes and it's range doesn't go beyond our villiage" Jon stated.
"Then how come when you wished the branch to be red, it didn't work?" Karyn asked.
Jon wished again for knowledge. Then he said, "Because everyone who lived in this town for long time traces their ancestry back to Incans."
"Which means, Everyone here has their limits on wishing stone, except..."