SQL Server Management Studio won't let me add an index to a table

sql-server, sql-server-2008, sql-server-2012, sql-server-2014, ssms

Solution

Solution: Close your table designers and database diagrams and try again. If that doesn't help, close all windows in Management Studio.

Cause: The "New Index" option gets disabled when the table is schema-locked by the designer window.

Problem

When I right click on the indexes folder in the table the "New Index" menu item is grayed out. I don't understand why. I've deleted all data in the table just in case, and refreshed and restarted SSMS, but no luck. I'm using SQL Server 2012 Business Intelligence SP1 CTP.

Original source