c# - A list of, list of ObservableCollection comes up null when looping through it -

I have a collection of compilations that are setup like the following.

  ObservableCollection & lt; ObservableCollection & lt; Image & gt; & Gt; _Documents_Completeclaims = New observable collection & lieutenant; OverviewCollection & lt; Image & gt; & Gt; ();   
 And I'm adding an archive to this list:  
  this._Documents_CompleteClaimsAdd (this._Documents_NewClaimList);   
  When I try to loop through the archive, it appears blank. There is one item in the collection:   
   
 But the collection number shows 0.  
   
 I used it just a few times ago, But with the list instead of ObservableCollection. Have worked well before any idea why the collections collections are not working? Or am I looking somewhat silly?  
 The problem is that I have incorrectly diagnosed this issue that there is no item in the collection in the collection.  
 In this way I was adding the collection to the list of collections:  
  this._Documents_CompleteClaimsAdd (this._Documents_NewClaimList); // Add claims to complete this list. Document_new climilar clean (); // Clear the list of claims so that we can start a new claim   
 I confirmed that there were items in the  document_ new climist list  collection, I can add that collection to the archive and then clear the  Document_NewClaimlist  collection. But if I comment it out Clear () line, it works just fine So I think the item must be removed in a different way. Maybe I can add items to a temporary collection, add that archive to the archive collection, and then clear the old archive. 
 
 
 There is something particularly wrong with what you posted. If you encounter the encounter  not , it was a false diagnosis. You've got a collection of archives, it contains an item which is empty which is empty I do not doubt that this is a bug, but this is not a bug in the code you posted.  
 Focusing on the code to add the best of that object to that empty collection.