I am getting the following error when trying to create a package using Courier.

Any insight would help! Thx in advance.

Umbraco.Courier.Core.Exceptions.PackageException: Unable to load item with id 'd25e4eb2-a89c-4610-be73-30f2efa2451a' from provider 'Datatypes' ---> Umbraco.Courier.Core.Exceptions.RetrieveException: Error retrieving item [d25e4eb2-a89c-4610-be73-30f2efa2451a] from provider [e0472592-e73b-11df-9492-0800200c9a66]. ---> System.Exception: Could not load assembly for datatype PDCalendar with dataEditorId 12f8603f-b284-4f84-9fc7-ef4c972e8d34 ---> System.NullReferenceException: Object reference not set to an instance of an object. at System.Object.GetType() at Umbraco.Courier.Persistence.V6.NHibernate.Persisters.DataTypeItem.RetrieveItem[T](ItemIdentifier itemId) in c:\Program Files (x86)\teamcity\buildAgent\work\650bafc4b83aa858\Core\Umbraco.Courier.Persistence.V6.NHibernate\Persisters\Datatype.cs:line 125 --- End of inner exception stack trace --- at Umbraco.Courier.Persistence.V6.NHibernate.Persisters.DataTypeItem.RetrieveItem[T](ItemIdentifier itemId) in c:\Program Files (x86)\teamcity\buildAgent\work\650bafc4b83aa858\Core\Umbraco.Courier.Persistence.V6.NHibernate\Persisters\Datatype.cs:line 146 at Umbraco.Courier.Core.ItemCrudProvider.RetrieveItem[T](ItemIdentifier itemId) --- End of inner exception stack trace --- at Umbraco.Courier.Core.ItemCrudProvider.RetrieveItem[T](ItemIdentifier itemId) at Umbraco.Courier.ItemProviders.DataTypeProvider.HandlePack(ItemIdentifier id) at Umbraco.Courier.Core.ItemProvider.Package(ItemIdentifier id) at Umbraco.Courier.RepositoryProviders.Local.Package(ItemIdentifier itemId) at Umbraco.Courier.Core.Packaging.RevisionPackaging.PackageItem(ItemIdentifier itemId, ItemProvider provider, QueuedItemIdentifier itemInQueue) --- End of inner exception stack trace --- at Umbraco.Courier.Core.Packaging.RevisionPackaging.PackageItem(ItemIdentifier itemId, ItemProvider provider, QueuedItemIdentifier itemInQueue) at Umbraco.Courier.Core.Packaging.RevisionPackaging.PackageBatch() at Umbraco.Courier.Core.Packaging.RevisionPackaging.PackageBatch() at Umbraco.Courier.Core.Packaging.RevisionPackaging.PackageBatch() at Umbraco.Courier.Core.Packaging.RevisionPackaging.PackageBatch() at Umbraco.Courier.Core.Packaging.RevisionPackaging.PackageBatch() at Umbraco.Courier.Core.Packaging.RevisionPackaging.Package() at Umbraco.Courier.Core.TaskManager.manageTask(IRevisionTask value) 3/12/2014 9:21:55 AM