Laying in shed

 I let my birds out of their electric fenced area in the mornings so they can free range. They have 2 sheltered areas that I have built and plenty of hedges/bushes etc but I also leave the shed door open. They know I keep the food in there and the bag of bedding and woodchips. The cream legbar (Sugar) started laying her egg on top of the straw bale and now they all lay there. The other day I put something on top to prevent them laying and they all went mad, rosey and screeching and making it very clear they wanted the bale back. How do I get them laying back in the nest boxes

Thanks

The original nest boxes are ok and, to be honest, ocassionally they do lay in there, perhaps because others are on the straw bale. 'Touch wood' I dont have red mite. Before I got the hens I doused the coop inside and out with poultry shield and do that once a month when I give the coop a thorough clean. I dust with Diatom weekly and (when we do get some sun) I put Diatom where they dust bathe. I also put Diatom in the euclyptus bedding in the nest boxes.  I thinkl I have just spoiled them and let them get away with it. 

Yes  it is eucalyptus straw which I use just for the nest boxes and woodchips for the floor