title: WPF Radio button does not update after several binding
body: <p>I have an application that allows users to move forward and backward
  <a href="https://i.stack.imgur.com/CROvk.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CROvk.png" alt="application with next back screens"></a>
  <br/>And the radio button is implemented like following:</p>
  
  <p><a href="https://i.stack.imgur.com/UblrR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UblrR.png" alt="radion button binding code"></a></p>
  
  <p><br/>For the first 4 times, I change the selected item for the radio button and then move next and then come back and do the same, the radio buttons work fine and the model is updated correctly as its GUI. However, after the first 4 times moving forwards and backwards, the radio buttons do not update its GUI.</p>
  
  <p><br/>
  <a href="https://i.stack.imgur.com/EIlvM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EIlvM.png" alt="enter image description here"></a></p>
  
  <p><br/> Following is the navigation system:
  <a href="https://i.stack.imgur.com/9vpJq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9vpJq.png" alt="enter image description here"></a></p>
  
  <p>Model and view are bound based on Next/Back button</p>
  
  <p>Check boxs works fine! 
  Please give me some suggestions.
  <br/>
  Thanks in advance</p>