Redmine

Hi, I have created a couple of custom fields and want to set the field permissions to them based on the status of the issue. For example, the custom field "Actual start" should be 'required' only when the issue status is 'In progress'. Like wise, the custom field 'Actual end' is 'required' only when the issue status is 'Resolved'. I set these permissions in the Workflow module, but they are not working when I create/update the issue.