Line 211 from components\com_virtuemart\controllers\productdetails.php
VmInfo (JText::_ ('YOU MUST LOGIN FIRST'));
just shows YOU MUST LOGIN FIRST for any language, instead of using the correct JText from the active language.
It should be corrected to:
VmInfo (JText::_ ('JGLOBAL_YOU_MUST_LOGIN_FIRST'));
thx, corrected