I am facing this error plx check it

[MandiC77984]

Error Message: An error occurred during the activation of a particular registration.
See the inner exception for details. Registration: Activator = DSUserService (ReflectionActivator),
Services = [Znode.Engine.Services.IUserService], Lifetime = Autofac.Core.Lifetime.MatchingScopeLifetime,
Sharing = Shared, Ownership = OwnedByLifetimeScope ---> An exception was thrown while invoking the constructor 'Void .ctor()'
on type 'DSUserService'. ---> Could not load file or assembly 'CTCT, Version=2.4.1.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies.
The system cannot find the file specified. (See inner exception for details.) (See inner exception for details.) User Referrer: drewshoe.nivisolutions.com Browser Name: Chrome UserId: Logger: Znode.Engine.Api.Client Debug Object Details: