[TYPO3-english] Fatal error: Cannot redeclare class tslib_tmenu_layers

[dd tt]

Hello,

When i'm trying to activate new extensions on Typo3 6.2 (simplecalendar for instance), I have this fatal error :

Fatal error: Cannot redeclare class tslib_tmenu_layers in $$/typo3conf/ext/gs_ts_template/tmenu_layers.php on line 452 

class tslib_tmenu_layers extends tslib_tmenu {
} 

I've been trying other extensions and I have the same error.

Any idea how to bypass this fatal error ? 


Thanks in advance for any suggestions (Be lenient, i'm a beginner  in Typo3)

T.