value reduceByKey is not a member of org.apache.spark.rdd.RDD

It's very sad.My spark version is 2.1.1,Scala version is 2.11

import org.apache.spark.SparkContext._
import com.mufu.wcsa.component.dimension.{DimensionKey, KeyTrait}
import com.mufu.wcsa.log.LogRecord
import org.apache.spark.rdd.RDD

object PV {

//
  def stat[C <: LogRecord,K <:DimensionKey](statTrait: KeyTrait[C ,K],logRecords: RDD[C]): RDD[(K,Int)] = {
    val t = logRecords.map(record =>(statTrait.getKey(record),1)).reduceByKey((x,y) => x + y)

I got this error

at 1502387780429
[ERROR] /Users/lemanli/work/project/newcma/wcsa/wcsa_my/wcsavistor/src/main/scala/com/mufu/wcsa/component/stat/PV.scala:25: error: value reduceByKey is not a member of org.apache.spark.rdd.RDD[(K, Int)]
[ERROR]     val t = logRecords.map(record =>(statTrait.getKey(record),1)).reduceByKey((x,y) => x + y)

there is defined a trait

trait KeyTrait[C <: LogRecord,K <: DimensionKey]{
  def getKey(c:C):K
}

It is compiled,Thanks.

 def stat[C <: LogRecord,K <:DimensionKey : ClassTag : Ordering](statTrait: KeyTrait[C ,K],logRecords: RDD[C]): RDD[(K,Int)] = {
    val t = logRecords.map(record =>(statTrait.getKey(record),1)).reduceByKey((x,y) => x + y)

Key need to override Ordering[T].

  object ClientStat extends KeyTrait[DetailLogRecord, ClientStat] {
      implicit val c

lientStatSorting = new Ordering[ClientStat] {
    override def compare(x: ClientStat, y: ClientStat): Int = x.key.compare(y.key)
  }

      def getKey(detailLogRecord: DetailLogRecord): ClientStat = new ClientStat(detailLogRecord)
    }