I found all the stones, got the prize and after a while came back there. I(actually the momba)forced elders attendant to work on the statue. Then I came to the workplace and they told me that they needed one skilled craftsman.(forgot his name). He refused to help ,and the Elder just said:What can we do(something like that). Is there a way to make him work so that the statue can be finished?

You have to go to Fisherman's Horizon. On the edge of town (where you fight the damaged Galbadian armoured vehicle) there's a house with a guy named Grease Monkey. Talk to him and he'll agree to help finish the statue.

thanks for the help!