Confluence 8 Web-item could not order following the "weight"

Hi all,
Our app was compatible with Confluence 7. And the order of web-item following the weight in the “atlassian-plugin.xml” file. Like this:
After update the app compatible with Confluence 8. And the “atlassian-plugin.xml” is the same, but the order of web-item was changed.

<!-- Web Items -->
  <web-item key="configuration" name="configuration" section="system.admin/ppp_section"
    <link linkId="configuration-link">

  <web-item key="export" name="Export Permission" section="system.admin/ppp_section" weight="200">
    <link linkId="export-configuration-link">

  <web-item key="import" name="Import Permission" section="system.admin/ppp_section" weight="300">
    <link linkId="import-configuration-link">

  <web-item key="audit-log" name="Audit Log" section="system.admin/ppp_section" weight="400">
    <label>Audit Log</label>
    <link linkId="audit-log-link">

Do you have any idea about it?
Thank you so much