2 answers
If you're getting a Bad Result instead of a Syntax Error, can you create a Report or a List View that displays all of the Fields in your Formula and the Formula results side-by-side and post a screenshot? It's gonna make troubleshooting the Formula a LOT easier if we can see the Input and the Output side-by-side.
Tips & Tricks: Measure twice and cut once with Formula QC List Views and Reports
https://success.salesforce.com/answers?id=9063000000046BfAAI