LandXML无法验证

Question

我有一个无法验证的XML模式。
错误：类型'http://www.landxml.org/schema/LandXML-1.2：curveType'不是简单类型或尚未声明。
但是类型是在以下模式中声明的：http://www.landxml.org/schema/LandXML-1.2/documentation/LandXML-1.2Doc.html

<?xml version="1.0" encoding="utf-8"?>

<xs:schema xmlns="http://www.landxml.org/schema/LandXML-1.2"
           targetNamespace="http://www.landxml.org/schema/LandXML-1.2"
           xmlns:xs="http://www.w3.org/2001/XMLSchema" 
           xmlns:ptoc="http://www.landxml.org/schema/LandXML-1.2"
           elementFormDefault="qualified"
           version="1.2">   
    <xs:element name="Curve">
        <xs:annotation>
        </xs:annotation>
        <xs:complexType>
            <xs:attribute name="rot" type="clockwise" use="required"/>
            <xs:attribute name="chord" type="xs:double"/>
            <xs:attribute name="crvType" type="curveType"/>
            <xs:attribute name="delta" type="angle"/>
            <xs:attribute name="desc" type="xs:string"/>
            <xs:attribute name="dirEnd" type="direction"/>
            <xs:attribute name="dirStart" type="direction"/>
        </xs:complexType>
    </xs:element>
    <xs:simpleType name="clockwise">
        <xs:restriction base="xs:string">
            <xs:enumeration value="cw"/>
            <xs:enumeration value="ccw"/>
        </xs:restriction>
    </xs:simpleType>
    <xs:simpleType name="spiralType">
        <xs:restriction base="xs:string">
            <xs:enumeration value="biquadratic"/>
            <xs:enumeration value="bloss"/>
            <xs:enumeration value="clothoid"/>
            <xs:enumeration value="cosine"/>
            <xs:enumeration value="cubic"/>
            <xs:enumeration value="sinusoid"/>
            <xs:enumeration value="revBiquadratic"/>
            <xs:enumeration value="revBloss"/>
            <xs:enumeration value="revCosine"/>
            <xs:enumeration value="revSinusoid"/>
            <xs:enumeration value="sineHalfWave"/>
            <xs:enumeration value="biquadraticParabola"/>
            <xs:enumeration value="cubicParabola"/>
            <xs:enumeration value="japaneseCubic"/>
            <xs:enumeration value="radioid"/>
            <xs:enumeration value="weinerBogen"/>
        </xs:restriction>
    </xs:simpleType>
</xs:schema>

我忘记了什么？