Unable to set restricted archictectures on a PPA

OOPS-2078CJ1072

Traceback (most recent call last):

    Module zope.publisher.publish, line 134, in publish
    result = publication.callObject(request, obj)
    Module canonical.launchpad.webapp.publication, line 498, in callObject
    return mapply(ob, request.getPositionalArguments(), request)
    Module zope.publisher.publish, line 109, in mapply
    return debug_call(obj, args)
    __traceback_info__: <security proxied zope.browserpage.metaconfigure.SimpleViewClass from /srv/launchpad.net/production/launchpad-rev-13900/lib/lp/soyuz/browser/../../app/templates/generic-edit.pt instance at 0x137104d0>
    Module zope.publisher.publish, line 115, in debug_call
    return obj(*args)
    Module canonical.launchpad.webapp.publisher, line 297, in __call__
    self.initialize()
    Module lp.app.browser.launchpadform, line 119, in initialize
    errors, action = form.handleSubmit(self.actions, data, self._validate)
    Module zope.formlib.form, line 689, in handleSubmit
    errors = action.validate(data)
    Module zope.formlib.form, line 602, in validate
    return self.validator(self.form, self, data)
    Module zope.formlib.form, line 548, in <lambda>
    callable = lambda form, *args: getattr(form, f)(*args)
    Module lp.soyuz.browser.archive, line 2135, in validate_save
    not self.context.canSetEnabledRestrictedFamilies(

ForbiddenAttribute: ('canSetEnabledRestrictedFamilies', <Archive at 0x126f4150>)<br />