Adding permission (Maven repo) to a Play Framework 2.1-RC4 project?

I am trying to add resolver to my 2.1.1 RC4 build file and get "not found: value resolvers" error

Any ideas what is going wrong?

import sbt._
import play.Project._

object ApplicationBuild extends Build {

val appName = "myappname"
val appVersion = "1.0-SNAPSHOT"

val appDependencies = Seq(
    "org.ocpsoft.prettytime" % "prettytime" % "2.1.2.Final",
    "com.twitter" % "cassie" % "0.19.0",
    jdbc,
    anorm)


val main = play.Project(appName, appVersion, appDependencies).settings(defaultScalaSettings: _*).settings(
    resolvers += "Twitter Repository" at "http://maven.twttr.com/"
)