Opacity mask remove material colors! why?

Im making a billboard OATMEAL BOX, dont ask why, so im made a material with opacity mask just to make the box edges transparent, like the one in the sprite on the right of the picture, but the masked object get broken, missing all the blue and dark parts, pls halp.

post pics of material graph and alpha of texture.

The opacity mask input wants a single value from 0-1, the first input of the texture sample is a group of 3 values which represent red, green, and blue.
Typically you make a black and white layer that you put in the alpha channel of your texture. So the bottom output on the texture sample would go into the opacity mask input.

could you show me? :3