我在这里使用MAX来挑选亿万富翁的净资产中的最大值，但在比尔·盖茨，埃隆·马斯克等情况下似乎不起作用

如何解决我在这里使用MAX来挑选亿万富翁的净资产中的最大值，但在比尔·盖茨，埃隆·马斯克等情况下似乎不起作用

SELECT disTINCT ?item ?itemLabel ?itemDescription (MAX(?billion) as ?billions) ?locationLabel (SAMPLE(?image) AS ?picture) ?page_titleEN
WHERE
{
  ?item wdt:P2218 ?worth.

  OPTIONAL {?item wdt:P19 ?location .}
  
  FILTER(?worth>1000000000).

  BIND(?worth/1000000000 AS ?billion).

  OPTIONAL {
    ?article schema:about ?item;

      schema:isPartOf <https://en.wikipedia.org/>;

      schema:name ?page_titleEN.

    ?item rdfs:label ?LabelEN.

    FILTER((LANG(?LabelEN)) = "en")

  }

  OPTIONAL { ?item wdt:P18 ?image. }

  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }

}
GROUP BY ?item ?itemLabel ?itemDescription ?billions ?locationLabel ?picture ?page_titleEN

ORDER BY DESC(?billions)