Service Notifications Mass change not possible - IW28

Hello colleagues,

I'm trying to do a mass change to a list Service Notification via PM/CS Transaction code IW28, but the "Carry out a mass change"  menu choice is greyed out.

I tried to search for existing posts, but haven't  found an answer.

Perhaps I'm missing something - is it some configuration that allows/dis-allows mass changes to Notifications?

Thanks in advance.

Regards,

Ivor Martin