Problem with develop of XML Schema based on an existent XML

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I have a problem with the validation of this piece of XML:\[code\]<?xml version="1.0" encoding="UTF-8"?><i-ching xmlns="http://www.oracolo.it/i-ching"> <predizione> <esagramma nome="Pace"> <trigramma> <yang/><yang/><yang/> </trigramma> <trigramma> <yin/><yin/><yin/> </trigramma> </esagramma> <significato>Questa combinazione preannuncia <enfasi>boh</enfasi>, e forse anche <enfasi>mah, chissa</enfasi>.</significato> </predizione> <predizione> <esagramma nome="Ritorno"> <trigramma> <yang/><yin/> <yin/> </trigramma> <trigramma> <yin/><yin/><yin/> </trigramma> </esagramma> <significato>Si prevede con certezza <enfasi>qualcosa</enfasi>, <enfasi>ma anche <enfasi>no</enfasi></enfasi>.</significato> </predizione></i-ching>\[/code\]This XML Schema was developed with Russian Dolls technique:\[code\]<?xml version="1.0" encoding="UTF-8"?><xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.oracolo.it/i-ching" targetNamespace="http://www.oracolo.it/i-ching" > <xsd:element name="i-ching"> <xsd:complexType> <xsd:sequence> <xsd:element name="predizione" minOccurs="0" maxOccurs="64"> <xsd:complexType> <xsd:sequence> <xsd:element name="esagramma"> <xsd:complexType> <!-- vi sono 2 trigrammi --> <xsd:sequence> <xsd:element name="trigramma" minOccurs="2" maxOccurs="2"> <xsd:complexType> <xsd:sequence minOccurs="3" maxOccurs="3"> <xsd:choice> <xsd:element name="yang"/> <xsd:element name="yin"/> </xsd:choice> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:sequence> <xsd:attribute name="nome" type="xsd:string"/> </xsd:complexType> </xsd:element> <!-- significato: context model misto --> <xsd:element name="significato"> <xsd:complexType mixed="true"> <xsd:sequence> <xsd:element name="enfasi" type="xsd:string" minOccurs="0" maxOccurs="unbounded"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType></xsd:element></xsd:schema>\[/code\]For exercise I have to develop an XML Schema to validate the previous XML. The problem is that oxygen says me this:\[code\]cvc-complex-type.2.4.a: Invalid content was found starting with element 'predizione'. One of '{predizione}' is expected. Start location: 3:6 End location: 3:16 URL: http://www.w3.org/TR/xmlschema-1/#cvc-complex-type\[/code\]why? is it something wrong with my xml schema?thank you very much