张经理最近碰到一件棘手的事。 公司花了一万多办下的ISO 9001证书，发给客户后，对方回复说：查不到。张经理蒙了——明明和某“认证公司”签了合同，审核老师来过现场，证书上也有编号、有印章，怎么就成了无效证书？
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