C# 应用程序错误：无法加载文件或程序集

我在.net上工作，当我运行我的应用程序时，我遇到了这个错误。有人能帮我吗

Application Error -
MESSAGE: Could not load file or assembly 'ConfigurationMgr, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.
SOURCE: BusinessLayer
TARGETSITE: Void .ctor()
STACKTRACE:
  at BusinessLayer.BL..ctor()
  at Marketing_BulkSMS..ctor()
  at ASP.marketing_bulksms_aspx..ctor()
  at __ASP.FastObjectFactory_app_web_q3yaaskd.Create_ASP_marketing_bulksms_aspx()
  at System.Web.Compilation.BuildResultCompiledType.CreateInstance()
  at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp, Boolean noAssert)
  at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath)
  at System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath)
  at System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig)

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bin文件夹中缺少ConfigurationMgr.dll文件，或者bin文件夹中的ConfigurationMgr.dll版本与Web.config中指定的版本不同