Search in mail not working

So I am having issues with 'searching' for emails, when Mail in open on my MacBook Pro. I click on the magnifying glass and type what email i want (it could be one i see directly in my inbox that I received the same day and have read it) and it will show '0 Found'. Why the heck is it not location the emails? I have gone into spotlight to make sure mail/messages is selected and it is. Am I missing another step? It has worked in the past.