UV Maps not showing in render

Question

I can not add all the images because the account is new and I don't have enough reputation.

I have an object (a tube of a cream) with three diferent materials, the base "plastic" material and I have created two separated materials to add the front and black labels to the tube.

The front and back label materials is the same as the "base material" but I'm trying to overlay the PNG image on top of it.

For doing that I have unwraped the parts of the object where the labels should go and placed the islands on top of the image.

I have created separated UV Maps for that purpose.

On the viewport view everything seems ok: As you can see the texture is correctly placed.

Render / Rendered view unexpected output: When rendering or in the rendered mode of the viewport the material with the UV Map appears as black.

Material nodes: For further info in case it's needed here are the screencaps of the material of the front label:

How can I solve this? Thank you!

Answer 1

Your shader node is a true mess

1. You have the an Alpha output connected to a Vector socket
2. The image Alpha is not connected to the group input Alpha socket
3. You are mixing a a Diffuse shader with a Transparent shader, that will lead to a transparent material, not black plastic
4. Then you are connecting Shaders (green) to a Color (yellow) socket
5. You are multiplying shaders, which I am not entirely sure what result it would yield
6. There is also a group "BaseMaskPlastic" with an unknown Shader output connected to a color socket

General rule of thumb: respect socket colors, match each type of data with it's own type of input, with the possible exception of Color/Value and Vector/Value which can at times be interchangeable.

You are also overcomplicating things a lot. If you want black color in the transparent areas of your image all it takes is one Diffuse shader and one Color Mix shader between the image and a black color and the image alpha as Mix Factor. Something in the like: