Hello Yaroslav,
May I know the version of the system you are using.
See if the new ADSO available in the system needs to be installed and activated first so that you will be able to activate your MP.
Kindly check whether you are able to view all the ADSO's available in the system under the ADSO tab of the multiprovider. All the available objects would be displayed only if the multiprovider is in change mode. Once after that, try to locate the old as well as the new ADSO /IMO/D_SD52 and ensure that the check box is unchecked for the old DSO.
Regards,
Vinoth V