Hen that doesnt lay?

  Hello everyone

I have six hens which are 9 months old...all of them have been laying eggs since 1st October last year and all the eggs are a good size. The hens have always laid eggs even throughout the winter...but I think I have a problem...5 of them lay everyday...yet one hen hasnt even started to lay yet!! 
When they come up to me they all curtsey...which shows the layers...yet one, the one that doesnt lay...doesnt curtsey..she seems thinner than the others too. 

Do you think I have a defect??...is there such a thing as a hen that doesnt lay? Or, do you think that this particular one was sold to me classed as a POL yet might have been a bit younger?

Any advice is warmly appreciated.  :happy:

Hello and thank you for getting back to me.

Well she is 36 weeks, which is why I thought she should be laying by now.

No I havent checked her vent...what would this tell me?

looe-looe-belle

I have 5 hens at the mo (was 6 but she went to the big chicken ranch in the sky) 4 of the girls have all laid eggs daily however 1 a cream legbar took forever she was hatched in march last year and laid her first egg last thursday ............. nher sister is currevtly sitting on her first clutch of eggs and doing well so dont worry about your girl just yet