Help. Layering Materials and Issues wth Transparancy on Textures


So i have a model i made. a simple target board for practicing shooting.
Im trying to add in a function so the user can set a face to the targetboard.

So i been trying to create a material that can layer another texture upon the 1st one at a spesific location.
I got this somewhat working… But i cant get the two layers to mix in properly.

I basically just want mat.b ontop of mat.a.
Im not sure if its someting wrong with my graph or if its my picures.i tried making the 2nd texture in many different formats.
png, psd, tga, tied both with alpha in the channel and with out. so im sure there is something else im missing here.

So Here is my Base Color material “Function” i created.

And her is the my 2nd function material i made for the face.

And here is the material that mixes them together and is what the mesh is set to use.

But as you can see. the result is not what i want.
Daffy Duck’s background is suppose to be transparant.
I can tweek the blend in with the two constants. but it dosent help.
Daffy Duck’s texture is still giving off a white background no matter what i do…
Also… there is some strange noice to addted to the output after the panning etc.
Not sure whats causing it. its verry noticeble as a cross.

anyone got an idea??