Scala:Implicits+；覆盖（&x2B；ReactiveMongo）

具有代码：

object MarketTrigger extends DbHandler[MarketTrigger]{
  implicit object BSONDateTimeHandler extends BSONHandler[BSONDateTime, DateTime] {
    def read(time: BSONDateTime) = new DateTime(time.value)
    def write(jdtime: DateTime) = BSONDateTime(jdtime.getMillis)
  }

  implicit val mtFormat = Macros.handler[MarketTrigger]
  override implicit val format = Macros.handler[MarketTrigger]
  ...

我得到了第二个隐式val的'value till'的

Implicit org.joda.time.DateTime错误，而第一个是正确的。对我来说有点奇怪。这是怎么回事