Situation:
When you try to book a resource like a conference room, for example, by using a resource mailbox that has been configured to automatically accept meeting requests, the meeting request is not automatically accepted. Additionally, you cannot book the resource, and you do not receive the following confirmation message:

The Calendar group schedule makes it easy for you to see the combined schedules of a number of people or resources at a glance.You can create and save multiple group schedules, each showing a group of people or resources.

While viewing a group schedule, you can quickly schedule a meeting with or send e-mail to some or all of the group members. You can get the latest free/busy information for each group member before you schedule a meeting, and you can use AutoPick to find a time that's free for all group members.

These instructions are for all resource types (Such as Conference Room, Projector, Meet Me Line, Training Room, TV etc) for checking the availability and scheduling.

Here is the Link of 17 tips for dealing with Outlook meeting requests