Runtime creation process is following. You have to have 'developer' user in device, which is created when mad-developer packet is installed, because 'mad remote' interface commands use 'developer' as a user. Developer have to have password when creation is done. When mad-developer packet is installed the developer has no password. Password can be created by mad-developer. When creation is completed password is not needed anymore, because creation creates rsa keys that are used further on. When runtime is created you can use it as long as IP address of the device remains same. Could it be possible that in your case the device IP address has been changed?