Hi im using the latest version of datefolders to manage my news and announcements but everytime i try to create a new announcement or news this error always shows up. can someone help me fix this probelm...

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.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.

Source Error: 

Stack Trace: 

[KeyNotFoundException: The given key was not present in the dictionary.]
   System.Collections.Generic.Dictionary`2.get_Item(TKey key) +14179127
   System.Collections.ObjectModel.KeyedCollection`2.get_Item(TKey key) +70
   Umbraco.Core.Models.ContentBase.GetValue(String propertyTypeAlias) +32
   InfoCaster.Umbraco.Common.DateFolders.GetItemDate(IContentBase content, String propertyAlias) +92
   InfoCaster.Umbraco.Common.DateFolders.Document_AfterSave(IContentService sender, SaveEventArgs`1 saveEventArgs) +306
   Umbraco.Core.Events.TypedEventHandler`2.Invoke(TSender sender, TEventArgs e) +0
   Umbraco.Core.Services.ContentService.SaveAndPublishDo(IContent content, Int32 userId, Boolean raiseEvents) +1129
   umbraco.cms.businesslogic.web.Document.SaveAndPublishWithResult(User u) +579
   umbraco.cms.presentation.editContent.Publish(Object sender, EventArgs e) +90
   System.Web.UI.WebControls.ImageButton.OnClick(ImageClickEventArgs e) +134
   System.Web.UI.WebControls.ImageButton.RaisePostBackEvent(String eventArgument) +204
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3804