TYPO3 Core

I have searched a lot, but I do not get any hint, why this should not work:

plugin.tx_cssstyledcontent_pi1 {
_LOCAL_LANG {
default {
label.toTop = Get me to the top!
}
de {
label.toTop = Bing mich nach oben!
}
}
}

It does not changed the text which is displayed via:

tt_content.stdWrap.innerWrap2 = | <p class="csc-linkToTop"><a href="#">{LLL:EXT:css_styled_content/pi1/locallang.xml:label.toTop}</a></p>

Why?

(issue imported from #M9327)