[yocto] PREFERRED_VERSION ignored

[Marco]

Hello,
using Yocto version 'rocko' I have a custom layer defining a new
recipe and a distro.
I have a recipe openssl_1.0.1u.bb in my meta-custom layer.
My meta-custom layer.conf has BBFILE_PRIORITY_meta-custom = "9"

In my meta-custom layer I have a distro configuration saying
PREFERRED_VERSION_openssl = "1.0.2o" so I expected to build 1.0.2o but
when I build bitbake openssl is always selected the 1.0.1u

Same problem if I set PREFERRED_VERSION_openssl = "1.0.2o" in the local.conf

Is there an issue or am I doing something wrong?

--
Marco