I have the following problem on IntelliJ IDEA 14:
I created a Play (Scala) project using the Activator (v1.2.10). Then, I converted it to an IDEA project using act
act
Apparently, this is a bug in some versions of IntelliJ 14, that just got fixed (as of version 14.0.3). Updating IJ then updating the scala plugin seems to make things work.