Button always in disabled state

Question

I've got a button with a simple command binding on my view:

<Window ...>
    <Window.DataContext>
        <vm:ShellViewModel />
    </Window.DataContext> 
    ...
    <Button Command="{Binding DoSomethingCoolCommand}" Content="Execute" />

And the vm:

public class ShellViewModel : ObservableObject {

    private RelayCommand _doSomethingCoolCommand;

    public ICommand DoSomethingCoolCommand {
        get {
            return _doSomethingCoolCommand ??
                (_doSomethingCoolCommand = new RelayCommand(DoSomethingCool));
        }
    }

    private void DoSomethingCool() { ... }

However, the button is disabled at application/view startup, and I can't get it enabled. I've tried passing a command execution evaluation to the RelayCommand and also set IsEnabled on the view. Am I missing something?

---

Edit

RelayCommand and ObservableObject are from the mvvm foundation project, as stated in the tags. Link: https://mvvmfoundation.codeplex.com

Answer 1

Did you check if any of the Buttons parents has it's state to disabled? This would also disable all child controls.

On a side-note:

You never seem to call CommandManager.InvalidateRequerySuggested() and it's not implemented in the RelayCommand class, just the registration of events, as seen here. ICommand or RelayCommand never does invalidate update it's state by default. You got to do this. Either by calling CommandManager.InvalidateRequerySuggested() which will suggest a requery of all registered Commands (since action in button 1, can have influence on many other commands.

For Example, there could be a IsProcessing property and when it's value is changed you could call CommandManager.InvalidateRequerySuggested() to update the state of all other Commands.