How can I use together alpha and shadow on surface shader?

Hello every one.

I'm trying to use together two feature on surface shader : alpha blending and receive shadow, but receive shadow is not working when alpha option is on. I maybe understand why the shadow not working, but I use that two together. so I trying to add surface shader pragma option 'addshadow', but is not working too. built in creator tree's leaf is working alpha blending and receive shadow. I want This! What option I add?

Sorry about that my bad english.

Unity doesn't support transparent objects with shadows unless they are cutouts like the leaves are. So you can't. Sorry.