提交表单时出现此错误：

org.hibernate.PersistentObjectException：分离的实体传递给持久化：com.project.pmet.model.Account;
嵌套异常是javax.persistence.PersistenceException：org.hibernate.PersistentObjectException：传递给持久对象的分离实体：com.project.pmet.model.Account

这是我的实体：

帐户：

@Entity
@DynamicInsert
@DynamicUpdate
public class Account {

    @Id
    @GeneratedValue
    private Integer id;

    @Column(nullable = false)
    private String login;

    @Column(nullable = false)
    private String password;

    @Column(nullable = false)
    private String email;

    @ManyToOne
    @JoinColumn(name = "team_id")
    private Team team;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "owner")
    private List<Team> ownedTeams;

    ...

球队：

@Entity
@DynamicInsert
@DynamicUpdate
public class Team {

    @Id
    @GeneratedValue
    private Integer id;

    @Column(nullable = false)
    private String name;

    @ManyToOne
    @JoinColumn(name = "owner_id", nullable = false)
    private Account owner;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "team")
    private List<Account> members;

    ...

这是控制器的一部分：

    @ModelAttribute("team")
    public Team createTeamObject() {
        return new Team();
    }

    @RequestMapping(value = "/teams/create-team", method = RequestMethod.GET)
    public String getCreateTeam(@ModelAttribute("team") Team team, Principal principal) {
        logger.info("Welcome to the create team page!");

        Account owner = accountService.findOneByLogin(principal.getName());
        team.setOwner(owner);
        team.setMembers(new AutoPopulatingList<Account>(Account.class));

        return "teams";
    }

    @RequestMapping(value = "/teams/create-team", method = RequestMethod.POST)
    public String postCreateTeam(@ModelAttribute("team") Team team) {
        logger.info("Team created!");

        teamService.save(team);

        return "redirect:/teams.html";
    }

以及形式：

<form:form commandName="team" id="teamForm">
      <div class="form-group">
          <label>Name</label>
          <form:input path="name" cssClass="form-control" />
      </div>
      <div class="form-group" id="row-template">
          <label>Members</label>
          <form:select path="members[0].id" cssClass="form-control" data-live-search="true" >
             <form:options items="${accounts}" itemValue="id" />
          </form:select>
          ...
      </div>
   <form:hidden path="owner.id" />
</form:form>

我究竟做错了什么？