UV baking a material with an alpha

I just tried this and it didn’t work and I wondered if anyone else had had any success.

I created a material that used a proceedural texture to affect the alpha. so in ‘map to’ the alpha button was pressed and the texture was multiplied. Works in a normal render but if you bake it you don’t get the alpha in the baked texture.

Anyone got this to work??

I have asked a guru, but it is the holiday so Im not sure when we will get the reply. Seems like it should work, since its just a procedural, you know?