Tail lite on 1999 Ford Windstar

How can I fix left tail light on 1999 Ford windstar van. I check for power and is none, traces the wire still no nothing. Cluster light indicating tail light malfunction. No matter what I do, no luck.I put a pig tail from right taillight to left, it work but the warning light at cluster stain on, I appreciate your help please. Thank, Luis Davila. I send this early, but is on a 1999 Ford windstar, not on my 2008 fusion. Yes every light work except left rear tail light. And I put a line electrical wire from right tail light to left tail light, it work but the warning light at cluster stain on, indicating tail light not working. So some where, where they meet is bad, but I don't know how to find it. Thank you Luis Davila