scala - Scalaz ValidationNel: traverse is not a member of List -

playing scalaz validationnel, trying transform list[validationnel[string, mytype]] validationnel[string, list[mytype]]

my code:

import scalaz._ import scalaz.syntax.traverse._ import scalaz.std.list._ import scalaz._  val ns: nodeseq = // ... val v: validationnel[string, list[mytype]] =    ns.tolist.traverse[({ type l[x] = validationnel[string, x] })#l, mytype](extractmytype(_))  private def extractmytype(n: node): validationnel[string, mytype] = //... 

when compiling sbt, get:

[error] myclass.scala:xx: value traverse not member of list[scala.xml.node]

[error] val v: validationnel[string, list[mytype]] = ns.tolist.traverse[({ type l[x] = validationnel[string, x] })#l, mytype](extractmytype(_))

i not traverseu work either version work before going further.

i using scala 2.10.0 , scalaz 7.1.1

where mistake?