force zypper to install a specific ersion

i have my own personal repo with older versions of rpms in it. If i want to install boost-license version 1.36.0.11.17 i do the following

zypper boost-license=1.36.0-11.17

this seems to be broken however as if i change the rev to one i know doesn't exist then it simply reverts to installing the latest rev instead of erro'ing which is stupid.

I find the only way to force zypper to installa specific rpm i want is to state the exact rpms URL httlp//mylocalrepository/myrpms/boost-1.36.0.11.17.src.rpm.

Any ideas how i can use zypper as it was designed to install a specific version and error if it doesnt exist?