Understanding how to label/target tensors for 3D volumes

I saw your post here that it is silmilar of my problem in this post.
for get non zeros argmax, if I don’t use relu in model and low learning rate, the accuracy in this model is very low.
what can i do for this?
Also, I wrote a model( with 3 conv and norm and without any activation function) that get accuracy 99% , but argmax is still zero!!