如何在学说中建立关系

我用Jobeet学习Symfony和Doctrine。我想在JobeetJob中添加关系。这是原件：http://www.symfony-project.org/jobeet/1_4/Doctrine/en/03

我确实喜欢这个：

JobeetCategory:
  actAs: { Timestampable: ~ }
  columns:
    name: { type: string(255), notnull: true, unique: true }
JobeetCategorya:
  actAs: { Timestampable: ~ }
  columns:
    name: { type: string(255), notnull: true, unique: true }
JobeetJob:
  actAs: { Timestampable: ~ }
  columns:
    category_id:  { type: integer, notnull: true }
    categorya_id:  { type: integer, notnull: true }
    type:         { type: string(255) }
    (...)
    expires_at:   { type: timestamp, notnull: true }
  relations:
    JobeetCategory: { onDelete: CASCADE, local: category_id, foreign: id, foreignAlias: JobeetJobs }
    JobeetCategorya: { onDelete: CASCADE, local: categorya_id, foreign: id, foreignAlias: JobeetJobsa }

当我这样做时：

php-symfony原则：build-all--并加载

我的有错误

SQLSTATE[23000]：完整性约束冲突：1452无法添加或更新子行：外键约束失败（jobeet.jobeet_job，constraint jobeet_job_categorya_id_jobeet_categorya_id foreign key（categorya_id）REFERENCES jobeet_categorya（id）ON DELETE CASCADE）

为什么？