Wing sexing chicks?

[australorp_breeder]

I'm getting the idea of wing sexing chicks, but I heard it's not reliable for all breeds of chickens. Can anyone please tell me if they've had any experience wing sexing any of the following breeds?:

Australorps
Jersey Giants
Cochins
Plymouth Rocks

I have crosses of all these chickens that are a day old and I would like to wing sex them.

 

[Wynette]

I've tried and have mostly been unsuccessful. I was told you can only wing sex with American breeds, but again, I've been unsuccessful. I'm beginning to wonder if it's only specific breeds you can do this with?

 

[australorp_breeder]

I was Googling and ironically it brought me to a thread here on BackYardChickens about feather sexing. The thread was from 2008, which is why I didn't reply to it. One member had said they believed it could only be done with certain breeds.