no declaration found for element 'n4:Envelope'

Question

I am not sure how to solve this error: no declaration found for element 'n4:Envelope'. I need to get a better understanding of xml schemas and how they are declared.

What declaration is it talking about?

Anyone can help on this?

This is the start of xml file:

<?xml version="1.0"?>
<n4:Envelope xmlns:http="http://schemas.xmlsoap.org/wsdl/" 
xmlns:n="http://www.informatica.com/wsdl/" 
xmlns:n4="http://schemas.xmlsoap.org/soap/envelope/" 
xmlns:n5="http://schemas.xmlsoap.org/wsdl/" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://www.informatica.com/wsdl/ Untitled1.xsd">
   <n4:Body>

This is the start of xsd file:

<?xml version="1.0"?>
 <xsd:schema targetNamespace="http://www.informatica.com/wsdl/" 
 elementFormDefault="qualified" 
 attributeFormDefault="unqualified" 
 xmlns="http://www.informatica.com/wsdl/" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
      <xsd:import namespace="http://schemas.xmlsoap.org/wsdl/http/"/>
         <xsd:element name="SHA003Bis_GetArticleDataResponse"
                      type="SHA003Bis_GetArticleDataResponseType"/>
         <xsd:element name="SHA003Bis_GetArticleDataRequest"
                      type="SHA003Bis_GetArticleDataRequestType"/>
         <xsd:complexType name="SHA003Bis_GetArticleDataRequestType">
            <xsd:sequence>