chain-build problem (was: Re: pkgconfig problem on RHEL-5)

... thanks as the new ffmpeg is not in the repo yet, I wanted to try chain-build as http://fedoraproject.org/wiki/PackageMaintainers/UsingKoji#Chained_builds suggests "when you want to rebuild a package against a just rebuilt dependency", but it failed: [kvolny@dhcp-lab-227 EL-5]$ make chain-build CHAIN='ffmpeg' make[1]: warning: jobserver unavailable: using -j1. Add `+' to parent make rule. make[1]: warning: jobserver unavailable: using -j1. Add `+' to parent make rule. usage: koji chain-build [options] target URL [URL2 [:] URL3 [:] URL4 ...] (Specify the --help global option for a list of other help options) koji: error: Unknown build target: el5-free make: *** [chain-build] Error 1 looks like a bug in Makefile to me, but as I've never used this feature, a misconfiguration/misuse on my side is highly probable ... any hints? K.