Problem at Spack Environment Load

[R-Witt]

Following the README in star-spack for STAR users I get the following:

$> source /cvmfs/star.sdcc.bnl.gov/star-spack/setup.sh
==> Added repo with namespace 'star'.
$> spack env list
==> 6 environments
star-x86-root5 star-x86-root6 star-x86-root624 star-x86_64-root5 star-x86_64-root6 star-x86_64-root624
$> spack find
==> 327 installed packages
-- linux-rhel7-x86 / gcc@4.8.5 ----------------------------------
apr@1.7.0 freetype@2.10.4 krb5@1.18.2 libxext@1.3.3 nlohmann-json@3.9.1 star-env@0.1
apr-util@1.6.1 ftgl@2.4.0 lhapdf@6.3.0 libxfixes@5.0.2 numactl@2.0.14 star-env@0.1
...

All is as expected. But the next command produces:

$> spack load star-env-root6 target=x86_64
==> Error: Spec 'star-env-root6 arch=linux-None-x86_64' matches no installed packages.