hasAccessLevel() doesn't work properly for access rights after upgrading XWiki

We upgraded from XWiki 1.2 to XWiki 1.7.2, and exported all created pages and spaces from the old to the new version. We created new users and groups in the new version, using the user names and group names that had been used for the old version.
Customizing the 'Quick Links' panel using code like

#if ($xwiki.hasAccessLevel("view","<space name>.WebHome"))

• <link>
  #end

works for the old settings (space rights for users and groups). However, it doesn't work for newly created spaces. It doesn't work for newly created groups either.