Mail doesn't "see" contacts. How to Fix?

Question

Some time ago, I pulled my Address book contacts into Maverick's Contacts, and this was successful; they're all there, categories, notes, comments..
However, Mail.app doesn't draw from any source when I begin to compose an email to people whose addresses should be in there..it Mail's little address book.
How can I restore that in Mail?
Thank you!

Answer 1

From the Mail menu bar, select
          Mail ▹ Preferences... ▹ Composing
and check the box marked
          Automatically complete addresses
You don't have to configure LDAP. If the box is already checked, or if checking it has no effect, then continue as below.
Please follow these directions to delete the Mail "sandbox" folders. In OS X 10.9 there are two sandboxes, while in 10.8 there is only one. If you're running a version older than 10.8, this comment isn't applicable.
Back up all data.
Triple-click anywhere in the line below on this page to select it:
~/Library/Containers/com.apple.mail
Right-click or control-click the highlighted line and select
          Services ▹ Reveal
from the contextual menu.* A Finder window should open with a folder named "com.apple.mail" selected. If it does, move the selected folder—not just its contents—to the Desktop. Leave the Finder window open for now.
Log out and log back in. Launch Mail and test. If the problem is resolved, you may have to recreate some of your Mail settings. You can then delete the folder you moved and close the Finder window.
This action will delete any custom Mail stationery that you have created. If you want to preserve it, ask for instructions.
If you still have the problem, quit Mail again and put the folder back where it was, overwriting the one that may have been created in its place. Repeat with this line:
~/Library/Containers/com.apple.MailServiceAgent
Caution: If you change any of the contents of the sandbox, but leave the folder itself in place, Mail may crash or not launch at all. Deleting the whole sandbox will cause it to be rebuilt automatically.
*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination  command-C. In the Finder, select
          Go ▹ Go to Folder...
from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.