c# - Grouping a LongListSelector containing ListBoxes inside ItemTemplate -

hello trying databind listboxes residing inside itemtemplate of lls, far have seen grouping applied template containing textblocks, need 'collection' being grouped by. know requirements not practical badly in need of it.

my model

public class itemviewmodel {     private string _id;     public string id     {                 {             return _id;         }         set         {             if (value != _id)             {                 _id = value;                 notifypropertychanged("id");             }         }     }     private string _lineone;     public string lineone     {                 {             return _lineone;         }         set         {             if (value != _lineone)             {                 _lineone = value;                 notifypropertychanged("lineone");             }         }     }      private string _linetwo;     public string linetwo     {                 {             return _linetwo;         }         set         {             if (value != _linetwo)             {                 _linetwo = value;                 notifypropertychanged("linetwo");             }         }     }  } 

my viewmodels

public class groupeditemviewmodel {     public string key2     {                 {             return _key2;         }         set         {             if (value != _key2)             {                 _key2 = value;                 notifypropertychanged("key2");             }         }     }     private observablecollection<itemviewmodel> _grp;     public observablecollection<itemviewmodel> groupeditems     {                 {             return _grp;         }         set         {             if (value != _grp)             {                 _grp= value;                 notifypropertychanged("groupeditems");             }         }      } }  public class mainviewmodel : viewmodelbase,inotifypropertychanged {     public mainviewmodel()     {         this.items = new observablecollection<itemviewmodel>();     }      public observablecollection<itemviewmodel> items { get; private set; }      public observablecollection<groupeditemviewmodel> groupedphotos     {                 {             var finalquery = items    .groupby(category => category.lineone)    .select(grouping => new groupeditemviewmodel { key2 = grouping.key,    groupeditems = grouping.toobservablecollection<itemviewmodel>() });              return new observablecollection<groupeditemviewmodel>(finalquery);          }     } 

}

my view - lls

<grid x:name="contentpanel">         <phone:longlistselector itemssource="{binding groupedphotos}" itemtemplate="{staticresource datatemplate3}" groupheadertemplate="{staticresource header}"/> </grid> 

my view - data template of lls

<datatemplate x:key="datatemplate3">         <grid>             <listbox itemssource="{binding groupeditems}" itemtemplate="{staticresource datatemplate4}" itemspanel="{staticresource itemspaneltemplate2}"/>         </grid> </datatemplate> 

my view - data template of listbox

<datatemplate x:key="datatemplate4">         <grid>             <textblock text="{binding lineone}"/>         </grid> </datatemplate> 

my view - data template of group header

<datatemplate x:key="header">         <grid>             <textblock text="{binding key2}"/>         </grid> </datatemplate>