when i deploy my project on server,i find this error. how to resolve  this problem?

Server Error in '/' Application.
--------------------------------------------------------------------------------

Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

Stack Trace:


[ReflectionTypeLoadException: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.]
   System.Reflection.RuntimeModule.GetTypes(RuntimeModule module) +0
   System.Reflection.Assembly.GetTypes() +159
   Nop.Core.Plugins.PluginManager.Initialize() +3301

[Exception: Could not initialise plugin folder]
   Nop.Core.Plugins.PluginManager.Initialize() +4549

[Exception: Could not initialise plugin folder]
   Nop.Core.Plugins.PluginManager.Initialize() +4782

[InvalidOperationException: The pre-application start initialization method Initialize on type Nop.Core.Plugins.PluginManager threw an exception with the following error message: Could not initialise plugin folder.]
   System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) +11697998
   System.Web.Compilation.BuildManager.CallPreStartInitMethods() +465
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1167

[HttpException (0x80004005): The pre-application start initialization method Initialize on type Nop.Core.Plugins.PluginManager threw an exception with the following error message: Could not initialise plugin folder.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11686928
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4863749


thanks for your help.