Chapter 18 shaders aren't working

[EricBL3]

Hi, I've been following the exercises in the book and I'm struggling with getting the diffuse & specular lighting to work in the last exercises of Chapter 18. I think that the problem is the calculation of the diffuse but I couldn't find the files for the shaders in the repo to check if I'm missing something. Here are some screenshots for reference of the content of my shaders:

texturedvert.vs

lighting.vs

result when running the program

If I remove the diffuse & specular from the result, I get the expected model without any lighting

I'm also able to add the ambient lighting without any problem