Swift包管理器(SPM)：导入库时出错

这是我的可执行文件的Package.swift：

import PackageDescription

let package = Package(
  name: "PayBackCodingChallenge",dependencies: [
    .package(url: "../NumberChecker",from: "1.0.0"),],targets: [
    .target(
      name: "PayBackCodingChallenge",dependencies: []),]
)

当我尝试在main.swift中导入NumberChecker时,我收到以下消息：没有这样的模块’NumberChecker’：

import NumberChecker

let arguments = CommandLine.arguments

if arguments.count != 3 {
  print("USAGE: PayBackCodingChallenge [data] [target]")
  print("  data: File containing list of numbers ")
  print("  target: Target number")
} else {
  let data = arguments[1]
  let target = arguments[2]
  print(data + " " + target)
}

我的NumberChecker库位于与PayBackCodingChallenge相同级别的目录中并正确编译.可能是什么问题呢？

提前致谢！