Outlook 2011 (Mac) Calendar Sharing Problem

Hi Guys

I am using Outlook 2011 for Mac and am wanting to share my calendar. I have had a look around on the web to see how I do this, but all information says the same thing, and that is that I should right click on the calendar and then click on permissions. However, my "permissions" tab is constantly greyed out.

Any ideas how I get around this?

Thanks in advance

Mark