What's app doesn't recognize a contact in my phonebook
First verify that the person actually has WhatsApp, because if they don't, it will not show up.

After you confirm the above, add the contact to your phone then open WhatsApp and press the green new chat icon on the bottom right. Now press on the three dots on the top right, and select 'refresh'

As long as you put in all area code info correctly and you did the above, it should show up.