The view model should implement the INotifyPropertyChanged interface and raise its PropertyChanged event when a value of a bound source property changes:
http://msdn.microsoft.com/en-us/library/windows/apps/system.componentmodel.inotifypropertychanged
You typically raise this event in the setter of the bound source property:
public string CustomerName
{
get
{
return this.customerNameValue;
}
set
{
this.customerNameValue = value;
NotifyPropertyChanged();
}
}
If you are using MVVM Light, your view model class can inherit from the ViewModelBase class and call its RaisePropertyChanged method, passing in the name of the source property:
public string CustomerName
{
get
{
return this.customerNameValue;
}
set
{
this.customerNameValue = value;
RaisePropertyChanged("CustomerName");
}
}
Please share your code for further help.