Hi Winnie,
Did you speak completely to the fisherman, and he asked you to help him with the traps? Did you place the bait on a stone to lure the crawfish?
Here's an excerpt from the walkthrough:
Go left of the fisherman's hut and look close at the 3 traps.
There are 3 traps with ropes colored red, green-blue and gray.
There are 3 stones marked green-blue male, red female and both symbols in one stone.
Place the bait on a stone.
When a crawfish comes, check the color and then click on the corresponding colored trap - either the red or the green.
Then click another trap and it will change to the color of the trap you initially clicked. Then click on the third trap to change it to that color also.
You're done when the bait disappears from inventory and you get out of the close-up mode.
