release version using c_cnt and b_cnt

I’ve the feeling I must be missing something simple here but googling and look on forum and ML archive didnt gave me a clear answer.
I would like the Release field from my spec file to be based on the osc build count and commit count. From what i do understand this should be the default behavior but it doesnt seem to be in my packages.
Example spec file header I’m using:

Name: iperf
Version: 2.0.4
Release: 3%{?dist}
Summary: Measurement tool for TCP/UDP bandwidth performance
License: BSD
Group: Applications/Internet
Patch0: iperf-2.0.4-debuginfo.patch
Patch1: iperf-2.0.4-tcpdual.patch
BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)

I tryed different variations of ‘release’ fields: “Release: 3”,“Release: <C_CNT>”,no release line … obvisouly none of it gives me the expected result.

I’m sure it must be very simple to get it to work as it should but if something can give me a hint on what to do I would appreciate.