wagtail:pagechooserpanel未显示

我正在尝试将PageChooserPanel添加到相关链接模型中,但它未显示在管理员中。我在迁移或加载页面时没有错误。代码如下:

sua_base/models.py版本:

class RelatedLinks(models.Model):

    page = models.ForeignKey(
        'wagtailcore.Page',
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='+',
    )

    title = models.CharField(max_length=255, blank=True)
    url = models.URLField("Embed URL", blank=True)

    panels = [
        FieldPanel('title'),
        PageChooserPanel('page'),
        FieldPanel('url'),
    ]

    class Meta:
        abstract = True
        verbose_name = "Related Link"
        verbose_name_plural = "Related Links"

app/models.py版本:

from sua_base.models import WebPage, Section, RelatedLinks

class SUAWebPage(WebPage):

        sidebar_content_panels = [
            InlinePanel('related_links', label="Related Links")
        ]

        edit_handler = TabbedInterface([
            ObjectList(content_panels, heading='Content'),
            ObjectList(sidebar_content_panels, heading='Sidebar'),
            ObjectList(WebPage.settings_panels, heading='Settings', classname="settings"),
            ObjectList(Page.promote_panels, heading='Promote'),
        ])

        class Meta:
            verbose_name = "SUA Web Page"
            verbose_name_plural = "SUA Web Pages"


    class SUAWebPageRelatedLinks(RelatedLinks, Orderable):
        page = ParentalKey(SUAWebPage, related_name='related_links')

其他两个字段( title 和 url )很好,只是PageChoosePanel不见了。