[TYPO3] Error with realty__search

[Frank Hüttner]

Hi,

i get the following error message when I activate "realty__search": 
Fatal error: Class 'tx_lib_translator' not found in 
/..../typo3conf/ext/realty__search/controllers/extended/class.tx_lib_translator_extended.php 
on line 3

Can somebody help me?

TYPO3 4.2.1
oelib 0.4.1
realty 0.1.2
realty__search 0.1.3