Salve ragazzi,
vorrei il vostro aiuto per capire dove sto sbagliando. Vi riporto di seguito i file con i quali sto lavorando e l'errore che si presenta.

File xsd:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.ibm.com/of/822/synonym/xml"
xmlns:esMapping="http://www.ibm.com/of/822/synonym/xml">
<xsd:element name="synonymgroups">
<xsd:complexType>
<xsd:sequence>
<xsd:element maxOccurs="unbounded" ref="esMapping:synonymgroup"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="synonymgroup">
<xsd:complexType>
<xsd:sequence>
<xsd:element maxOccurs="20" minOccurs="2" ref="esMapping:synonym"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="synonym" type="xsd:string"/>
</xsd:schema>


file xml da me creato

<?xml version="1.0" encoding="UTF-8"?>
<synonymgroups xmlns="http://www.ibm.com/of/822/synonym/xml">
<synonymgroup>
<synonym>NOme1</synonym>
<synonym>NOme2</synonym>
<synonym>NOme3/synonym>
</synonymgroup>
<synonymgroup>
<synonym>NOme4</synonym>
<synonym>NOme5</synonym>
<synonym>NOme16/synonym>
</synonymgroup>
<synonymgroup>
<synonym>NOme7</synonym>
<synonym>NOme8</synonym>
<synonym>NOme9</synonym>
</synonymgroup>
</synonymgroups>


Errore riscontrato:
cvc-elt.1: Cannot find the declaration of element 'synonymgroups'.
Location: (2, 62)


sapreste aiutarmi per favore?
Grazie