global disable() method not recognised?

[Stephen Cameron]

Hi,

I'm trying to make an object view-only for some of its lifecycle, but the
global disable() action method indicated in the documentation is not being
recognised as a special one, ie:

    public String disable(Identifier.Type identifierType) {
        return (!getStatus().equals(Status.ACTIVE))
                ? "Only ACTIVE Participants can be edited"
                : null;
    }

I get a 'Disable' action button appearing on the page. Am I missing some
detail?

Thanks