No results found to publish. Unit tests in Azure DevOps build

I tried to configure my build to run the unit tests of the project but I should be doing something wrong.

The structure of my project is something like this (using .NET Framework 4.6.1):

Solution 'Project.Testing'
    Project1.XXXX
    Project1.XXXX.Test
    Project2.XXXX
    Project2.XXXX.Test

But I'm getting this report:

Any idea of what's happening? Thanks in advance!