spack -C /user-environment/config load xy not working

[simonpintarelli]

spack -C /user-environment/config activate -d and load shows:

==> Error: `spack env activate` requires Spack's shell support.
  
  To set up shell support, run the command below for your shell.
  
  For bash/zsh/sh:
    . /bret/scratch/cscs/simonpi/spack-0.21.2/share/spack/setup-env.sh

Despite spack shell support has been loaded via source spack/share/spack/setup-env.sh