I have a problem with email if a user join a group

The EMail to Admin contains following text:

COM_COMMUNITY_GREETING
COM_COMMUNITY_GROUPS_EMAIL_NEW_MEMBER_JOINED

where is the problem?

Hi Jens,

please check it at language files
/language/[language]/[language].com_community.ini:
must be missing that language variable. for English like this:

COM_COMMUNITY_GREETING="Hi {target},"
COM_COMMUNITY_GROUPS_EMAIL_NEW_MEMBER_JOINED="%1$s joined your group, %2$s \n\nTo view the group, follow the link below:\n\n <a href=_QQQ_{url}_QQQ_>{url}</a>"

Hi Jens,

We have not received any response back from you in over 7 days, and would like to know if you consider this issue to be resolved. If you have any further questions, simply reply to this post.

Regards,
Albert