Can't get hen to lay in nesting box

[Chicken2.01]

My 20 week old white leghorn just started laying and she won't lay in the nesting box, instead she flys out of the run into the yard and lays in a black tub full of dirt. I put golf balls in the nesting boxes to help but no luck.

 

[Kiki]

Can you keep her locked up in the coop for a few days?

 

[aart]

Can you keep her locked up in the coop for a few days?

...and cover your run so she can't fly out?