OBS does not find source file - for some distros at least

Gents,
I wanted to build a new version of zyGrib. The source file is imported via a service. That worked and the build for openSUSE 12.1 and 12.2 went fine.

But for 12.3 the log file claims:

error: File /home/abuild/rpmbuild/SOURCES/zyGrib-6.1.3.tgz: No such file or directory

Is there a difference in OBS between 12.1/2 and 12.3? Trigger rebuild did not help…