chickens keep sitting in nest box and singing egg song--but no egg

[eggsontoast]

I have 3 chickens-one, maybe two, are laying. Both go into the nest box frequently and sit with their tail high up in the air. They also sing the "egg song". But when I go out there to retrieve an egg....NOTHING!!! I thought I'd have more eggs by now, but all but one have been soft-shelled. Where are my freakin' eggs??!!

 

[eggsontoast]

UPDATE: my black orp is laying every other day. My buff orp, however, laid six soft shelled eggs in a 2 week period and nothing since. Is she not going to lay now? Could something be wrong with her? Thw whole reason i got orps was because i was told they were excellent layers. I've fallen in love with her but cant help being disappointed about her egg production. Any advice?