W4 View History >> Server error observed on View History screen.

on View History screen, while all items in 'Document Sub Type' list and 'Users' list are selected, server error occurred on Search. PFA screen shot and error log.

exception : Object reference not set to an instance of an object.
App Error Log : -
Employee ID : 26
Action Name : ViewHistory
Model : System.Web.Mvc.HandleErrorInfo
Controller : UserDetails
Web Error Log : at WORKTERRA.Shared.WORKTERRAControllerWebTier.GetCollection(ObjectType I_objectType, Hashtable I_criteria, String I_AdditionalCriteriaString, Object I_context, Boolean I_mode, Boolean I_needCollection) in d:\WT\branches\LB\Web\ControllerWebTier\ControllerWebTier\WORKTERRAControllerWebTier.cs:line 335
at WORKTERRA.Shared.Areas.UserDetails.Models.ViewHistory.AddHistoryCriteriaModel.PopulateHistoryInformation() in d:\WT\branches\LB\Web\Web Projects\WORKTERRA\Areas\UserDetails\Models\ViewHistory\AddHistoryCriteriaModel.cs:line 313
at WORKTERRA.Shared.Areas.UserDetails.Controllers.UserDetailsController.ViewHistory(AddHistoryCriteriaModel objAddHistoryCriteriaModel) in d:\WT\branches\LB\Web\Web Projects\WORKTERRA\Areas\UserDetails\Controllers\ViewHistory\HistoryController.cs:line 36
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.<>c_DisplayClass15.b_12()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)