UV mapping in cycles

I have a model where some vertices are in a group and have a different material that has a uv mapped texture. The material is defined with nodes and I it works for me on a simple cube. However with the model I have as soon as I go into edit mode it doesn’t show the image anymore. I use the same image as in the node definition of the material.
I got it to work once when I made the whole object the same material. But after I assigned some vertices to another material without the UV mapping, I coouldn’t se the image anymore in the UV editor. I haven’t found any other posts mentioning this problem , so I’m probably doing something wrong but what…
Thanks in advance for any hints

Hy buddy
Are you sure that every single vertex has been applied to a material group?
If not, this would probably be the problem.

Let’s say you got 2 materials and apply 10 of 50 vertecies to the first material.
Then you also need to apply the other 40 vertecies to the secont material.

Are you shure you did this?