Plugin localization

i18n
#1

i wrote a plugin (SiteTheme) as a theme and i want to localize it.
i generate pot file using

bin\cake i18n extract --plugin SiteTheme

the pot file created by bake at

root/plugins/SiteTheme/src/Locale/default.pot

i moved it to

root/plugins/SiteTheme/src/Locale/en_US/default.po

and i set the locale to en_US
but cakephp dose not load it .
but when i move files to the

root/src/Locale/en_US/default.po

it loads perfectly.
the question is how can i load po files in the plugins directory ?

i cleared the root/tmp/cache/persistent every time i test