PackTexture doesn't work in flash platform?

I’m trying to port my project to flash. And I get an error “Texture atlas needs textures to have Readable flag set!” from this line of code.

rectUV = texture.PackTextures(inputTexture, padding, 1024, true);

This works perfectly fine in PC and iOS. I’ve already set read/write enable of every textures in inspector. Is this a bug or not?

Finally I figured it out how to make runtime PackTexture works in Flash:

The Unity default Texture Format of Flash is either RGB or RGBA JPG Compressed, I override for FlashPlayer for the Texture Format to RGB 24 or 32bit, then it has no problem in Flash.