[TYPO3-project-seminars] How to change Stings in seminars/BackEnd/locallang.xml

[Malte Frerichs]

Hello,
I am looking for a way tou change the default mail-text which is shown 
after pressing the confirmation-button for a seminar in the backend 
(confirm/cance Emails).
The default text is located in ext/seminars/BackEnd/locallang.xml but I 
am not shure how to overwrite this in my template.

In the manual there was only written the way for the locallang's in 
seminars (plugin.tx_seminars._LOCAL_LANG.de.), pi1 
(plugin.tx_seminars_pi1._LOCAL_LANG.de.) and pi2 
(plugin.tx_seminars_pi1._LOCAL_LANG.de.).
I tried it with
plugin.tx_seminars_BackEnd._LOCAL_LANG.de.confirmMailForm_prefillField_messageBody

but nothing changed.

Is there another way to change the text or do I have to edit the file?

Greetings

Malte