Developer Toolkit for CRM Online 2015

Metadata contains a reference that cannot be resolved: 'https://example.api.crm4.dynamics.com/_common/error/errorhandler.aspx?BackUri=&ErrorCode=&Parm0=%0d%0a%0d%0aتفاصيل الخطأ: 
The service '%2fXRMServices%2f2011%2fDiscovery.svc' cannot be activated due to an exception during compilation. 
The exception message is: Could not load file or 
assembly 'Microsoft.Crm.Site.Services%2c Version%3d7.0.0.0%2c Culture%3dneutral%2c PublicKeyToken%3d31bf3856ad364e35' or one of its dependencies. 
The system cannot find the file specified..&RequestUri=%2fXRMServices%2f2011%2fDiscovery.svc%3fwsdl&user_lcid=1025'.