Play Framework: IntelliJ IDEA cannot find declaration to go to

I'm doing a Play! Framework project, and all of a sudden, IntelliJ IDEA forgets about everything, doesn't provide any autocomplete / intellisense, doesn't check syntax, doesn't check my imports, nada, kinda just a text-editor like Sublime at that point.

What I'm using:
- play! framework 2.3.5
- IntelliJ IDEA 13.5.1
- SBT 0.13.5
- Mix of Java and Scala
- Activator UI
- OSX Maverick

Bascially my issue/sympton is: IntelliJ cannot find declaration to go to in Play Framework, and provides no autocomplete / syntax check support.

Stack Overflow had me Invalidate Caches and Restart. ehh, wasn't enough.

Solution: Specify JDK for Scala to JDK 1.7

I'm on OSX, so Linux/Windows users will have to ad-lib.
IntelliJ -> Preferences -> IDE Settings -> Scala -> JVM SDK
Mine was oddly set to , thus nothing worked, so I flipped it to JDK 1.7, and then re-ran Invalidate Caches and Restart. A few minutes later, and I'm back in business.