scala – 无法使用Anorm读取Integer列

import play.api.db.DB
import anorm._
import org.joda.time.DateTime
import AnormExtensions._ // https://stackoverflow.com/a/11975107/11236
import play.api.Play.current
import java.util.Date

var stream = SQL("SELECT amiId,created,version FROM Amis WHERE created = {maxCreated}")
    .on("maxCreated" -> new Date(maxCreated.getMillis))
    .apply()

val map: Stream[Ami] = stream.map { ami =>
    val s: String = ami[String]("amiId")
    val date: Date = ami[Date]("created")

    // The following line throws a compilation error
    var version: Integer = ami[Integer]("version")

    new Ami(s,new DateTime(date),version)
}

我得到一个编译错误：找不到参数c的隐式值：anorm.Column [Integer]

这有什么问题？如果我能阅读日期,为什么我不能阅读整数？