Src-resolve.4.2: Error Resolving Component 'ds:Signature'

I am validating an XML from an xsd but I have an error when I say that it has to validate a signature tag

this is the XML:

<?xml version="1.0" encoding="UTF-8"?>
<ValidaLinea>
    <cveBanco>40058</cveBanco>
    <importe>0</importe>
    <fechaHoraEnvio>2002-05-30T09:00:00</fechaHoraEnvio>
    <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">...
    </Signature>
</ValidaLinea>

and this is the XSD

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"  
           xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
           >
<xs:complexType name="ValidaLinea">
    <xs:sequence>
        <xs:element name="cveBanco">
            <xs:simpleType>
                <xs:restriction base="xs:string">
                    <xs:pattern value="[0-9]{5}" />
                </xs:restriction>
            </xs:simpleType>
        </xs:element>
        <xs:element name="importe">
            <xs:simpleType>
                <xs:restriction base="xs:long">
                    <xs:totalDigits value="14" />
                </xs:restriction>
            </xs:simpleType>
        </xs:element>
        <xs:element name="fechaHoraEnvio">
            <xs:simpleType>
                <xs:restriction base="xs:dateTime">
                </xs:restriction>
            </xs:simpleType>
        </xs:element>
        <xs:element name="Signature" type="ds:Signature"/>
    </xs:sequence>
</xs:complexType> 
<xs:element name="ValidaLinea" type="ValidaLinea"/>
</xs:schema>

the error that shows me when I try to do the validation is the following:

Src-resolve.4.2: Error Resolving Component 'ds:Signature'.
It Was Detected That 'ds:Signature' Is In Namespace 'http://www.w3.org/2000/09/xmldsig#',
But Components From This Namespace Are Not Referenceable From Schema Document 'null'.