In the past we set up a user called "Training Room." When people needed to schedule that room, they included that "user" as an attendee in an Outlook meeting request. The invitation to the meeting appeared in my mailbox, and not in a mailbox for Training Room. When I clicked the Calendar button on the meeting invitation, it checked the calendar for the Training Room, and when I accepted the invitation it appeared on the calendar for the training room.

Something has changed - possibly when we moved mailboxes to different stores. In any event, I can't figure out how to get back the former functionality which worked so well. Now, the meeting invitation appears in my mailbox, but it checks my calendar (not the training room's) and if I accept it puts the meeting on my calendar, not the training room's. I've gone into Outlook using the Training Room profile, and have set myself up as a delegate for Training Room, with editor permissions and checked the box about "Delegate receives copies of meeting requests sent to me." Obviously, that works, because I get the meeting requests. I've also set it up to send requests only to me, which seems to work, too. But it still checks my calendar and puts the items on my calendar, instead of the Training Room's calendar.
What am I/are we missing?

Any thoughts will be appreciated. Thank you.