error causing wsdl

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<wsdl:definitions xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
    xmlns:tns="http://www.example.com/AdapterDSS/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema" name="AdapterDSS"
    targetNamespace="http://www.example.com/AdapterDSS/">
    <wsdl:types>
        <xsd:schema targetNamespace="http://www.example.com/AdapterDSS/">
            <xsd:element name="Sign">
                <xsd:complexType>
                    <xsd:sequence>
                        <xsd:element name="userId" type="xsd:string" />
                        <xsd:element name="fileType" type="xsd:string"></xsd:element>
                        <xsd:element name="fileContent" type="xsd:base64Binary"></xsd:element>
                    </xsd:sequence>
                </xsd:complexType>
            </xsd:element>
            <xsd:element name="SignResponse">
                <xsd:complexType>
                    <xsd:sequence>
                        <xsd:element name="signature" type="xsd:base64Binary" />
                        <xsd:element name="status" type="xsd:string"></xsd:element>
                    </xsd:sequence>
                </xsd:complexType>
            </xsd:element>
        </xsd:schema>
    </wsdl:types>
    <wsdl:message name="SignRequest">
        <wsdl:part element="tns:Sign" name="parameters" />
    </wsdl:message>
    <wsdl:message name="SignResponse">
        <wsdl:part element="tns:SignResponse" name="parameters" />
    </wsdl:message>
    <wsdl:portType name="Adapter">
        <wsdl:operation name="Sign">
            <wsdl:input message="tns:SignRequest" />
            <wsdl:output message="tns:SignResponse" />
        </wsdl:operation>
    </wsdl:portType>
    <wsdl:binding name="AdapterSOAP" type="tns:Adapter">
        <soap:binding style="document"
            transport="http://schemas.xmlsoap.org/soap/http" />
        <wsdl:operation name="Sign">
            <soap:operation soapAction="http://www.example.com/AdapterDSS/Sign" />
            <wsdl:input>
                <soap:body use="literal" />
            </wsdl:input>
            <wsdl:output>
                <soap:body use="literal" />
            </wsdl:output>
        </wsdl:operation>
    </wsdl:binding>
    <wsdl:service name="Adapter">
        <wsdl:port binding="tns:AdapterSOAP" name="AdapterSOAP">
            <soap:address location="http://localhost:7001/AdapterDSS/" />
        </wsdl:port>
    </wsdl:service>
</wsdl:definitions>