Web Part Error: A Web Part or Web Form Control on this Page cannot be displayed or imported. The type COL.SharePoint.WebParts.COL_CourseDetails.COL_CourseDetails, COL.SharePoint.WebParts, Version=1.0.0.0, Culture=neutral, PublicKeyToken=904f723db6208274 could not be found or it is not registered as safe. Correlation ID: 8b7826a1-d46c-d0c0-9c9c-93c044d1e52d.

Error Details:
[UnsafeControlException: A Web Part or Web Form Control on this Page cannot be displayed or imported. The type COL.SharePoint.WebParts.COL_CourseDetails.COL_CourseDetails, COL.SharePoint.WebParts, Version=1.0.0.0, Culture=neutral, PublicKeyToken=904f723db6208274 could not be found or it is not registered as safe.]
  at Microsoft.SharePoint.ApplicationRuntime.SafeControls.GetTypeFromGuid(Boolean isAppWeb, Guid guid, Guid solutionId, Nullable`1 solutionWebId, String assemblyFullName, String typeFullName, Boolean throwIfNotSafe)
  at Microsoft.SharePoint.WebPartPages.SPWebPartManager.CreateWebPartsFromRowSetData(Boolean onlyInitializeClosedWebParts)