There is an error in the ypserv build that prevents successful updates of a slave NIS server from the master, only leaving the intermediate map files (<mapname>~.db) on the slave. This issue is mentioned in the README and BUGS files that come with the ypserv source, but the solution is not implemented in the spec file for the package. I emailed the author and he confirmed this. Time for a rebuild...
BTW, the fix is to delete the --with-ndbm=yes flag and recompile
this is fixed in the errata release....