Problem with UninstallCaption and multiple languages

Has anyone encountered problems using UninstallCaption for English and Japanese.

UninstallCaption /LANG=${LANG_ENGLISH}  "Uninstall"
UninstallCaption /LANG=${LANG_JAPANESE} "Uninstall in Japanese" 

This isn't working for me. The English version is displayed everytime. Any thoughts on why this might be happening. I suspect I've messed up the script somewhere.

It should work. If you suspect you've messed something in the script then the script is needed to find the problem.