Error access to Media Manager

Hi,
when i try to use the Media Manager on a new article i can't list the folder.
I receive this error :

Fatal error: Call to a member function getTag() on a non-object in /home/motfradd/public_html/libraries/cms/application/site.php on line 436

I obtain the following error too when i

Uncaught TypeError: Cannot call method 'meta' of undefined easyblog-3.9.15110.optimized.min.js:172

when i click to send a media :

Uncaught TypeError: Cannot call method 'place' of undefined easyblog-3.9.15110.optimized.min.js:171

If i have a look to firebug :

Fatal error: Uncaught exception 'RuntimeException' with message 'Unable to load renderer class' in /home/motfradd/public_html/libraries/joomla/document/document.php:1020Stack trace:#0 /home/motfradd/public_html/templates/rt_chapelco/features/dropdownmenu.php(46): JDocument->loadRenderer('module')#1 /home/motfradd/public_html/libraries/gantry/core/renderers/gantrymodulesrenderer.class.php(65): GantryFeatureDropdownMenu->render('header-a')#2 /home/motfradd/public_html/libraries/gantry/core/gantry.class.php(867): GantryModulesRenderer::display('header', 'standard', 'standard', '12', NULL)#3 /home/motfradd/public_html/templates/rt_chapelco/error.php(45): Gantry->displayModules('header', 'standard', 'standard')#4 /home/motfradd/public_html/libraries/joomla/document/error/error.php(135): require_once('/home/motfradd/...')#5 /home/motfradd/public_html/libraries/joomla/document/error/error.php(107): JDocumentError->_loadTemplate('/home/motfradd/...', 'error.php')#6 /home/motfradd/public_html/libraries/legacy/error/error.p in /home/motfradd/public_html/libraries/joomla/document/document.php on line 1020

Could you help ?
I use Chapelco from rocketthemes.
Regards,
Olivier