How to check a dialog been registered

[hengway]

I did register a dialog by code below

_containerRegistry.RegisterDialog<ConfirmationView>(ViewName.DialogConfirmation);

I had try to check did this class or name been register by code below:

_containerRegistry.IsRegistered<ConfirmationView>(ViewName.DialogConfirmation);
 _containerRegistry.IsRegistered(typeof(ConfirmationView));

seem like none of the code working, all return "false"

Can please advice