c# - Binding doesn't subscribe to PropertyChangedHandler -

alright i've been on ages , can't see why doesn't work.

i have binding usercontrol label onto property in class cell. class implements interface inotifypropertychanged. there everytime set method called call onpropertychanged("value)which expected update label it's binded to. not case.

i did research on stack clarify of problems i've checked:

i have datacontext set since use mvvm light set viewmodel locator.

this property outside of viewmodel it's suppose in order not make more expandable towards other sizes of sudoku.

edit: property changed fired handler null suspect it's not being subscribed to, hence title.

edit 2 code sudoku game grid of 3x3 grids of 3x3 hiarchy here outtergrid has innergrids , innergrids have cells thought better not include these codes since same.

snipit of datacontext declared mainwindow.window:

<window x:class="sudokuwpf.mainwindow"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:local="clr-namespace:sudokuwpf"     datacontext="{binding main, source={staticresource locator}}"     title="sudokuwindow" height="350" width="525"> 

here code of cell class

public class cell : inotifypropertychanged {     private int _value;        public int value     {         { return _value; }         set         {             _value = value;             //content = _value;             onpropertychanged("value");         }      }       public event propertychangedeventhandler propertychanged;      [notifypropertychangedinvocator]     protected virtual void onpropertychanged([callermembername] string propertyname = null)     {         var handler = propertychanged;         if (handler != null) handler(this, new propertychangedeventargs(propertyname));     } } 

and binding in usercontrol

<usercontrol x:class="sudokuwpf.usercontrolsudoku"          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"          xmlns:localcontrol="clr-namespace:sudokuwpf"          xmlns:d="http://schemas.microsoft.com/expression/blend/2008"          xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:ignorable="d"          horizontalalignment ="stretch"          horizontalcontentalignment ="stretch"          verticalalignment ="stretch"          verticalcontentalignment ="stretch"          foreground="white"          width="{binding relativesource={relativesource self}, path=actualheight}"> <usercontrol.resources>      <localcontrol:cell x:key="cell"></localcontrol:cell>     <localcontrol:innergrid x:key="innergrid"></localcontrol:innergrid>     <localcontrol:outergrid x:key="outergrid"></localcontrol:outergrid>      <datatemplate x:key="celltemplate">         <border x:name="border" borderbrush="aliceblue" borderthickness="1">             <label content="{binding source={staticresource cell}, path=value, updatesourcetrigger=propertychanged}"></label>         </border>     </datatemplate> 

any appreciated.

alright after wrongfully eliminating datacontext out of problem turned out core of problem. binded datacontext outer grid object this:

<usercontrol x:class="sudokuwpf.usercontrolsudoku"          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"          xmlns:d="http://schemas.microsoft.com/expression/blend/2008"          xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:ignorable="d"          horizontalalignment ="stretch"          horizontalcontentalignment ="stretch"          verticalalignment ="stretch"          verticalcontentalignment ="stretch"          foreground="white"          width="{binding relativesource={relativesource self}, path=actualheight}"          datacontext="{binding source=outergrid}"         >   public outergrid outergrid = new outergrid();     public usercontrolsudoku()     {         initializecomponent();         mainlist.datacontext = outergrid;     }