title: Cannot find the declaration of element 'bookstore'
body: <p>I am a beginner for XMl and XSD.I have developed XML and XSD file.I used <a href="https://www.liquid-technologies.com/online-xsd-validator" rel="nofollow noreferrer">Liquid</a> online xml validater to validate my XML file against my XSD.When I try to to validate my XML I got error "cvc-elt.1.a: Cannot find the declaration of element 'bookstore'.". How can I fix this issue?</p>
  
  <p>This is my XML</p>
  
  <pre><code>&lt;bookstore xmlns="http://www.contoso.com/books"&gt;
    &lt;book genre="autobiography" publicationdate="1981" ISBN="1-861003-11-0"&gt;
      &lt;title&gt;The Autobiography of Benjamin Franklin&lt;/title&gt;
      &lt;author&gt;
        &lt;first-name&gt;Benjamin&lt;/first-name&gt;
        &lt;last-name&gt;Franklin&lt;/last-name&gt;
      &lt;/author&gt;
      &lt;p&gt;
        &lt;price&gt;10&lt;/price&gt;
        &lt;price&gt;10&lt;/price&gt;
        &lt;price&gt;20&lt;/price&gt;
      &lt;/p&gt;
    &lt;/book&gt;
  &lt;/bookstore&gt;
  </code></pre>
  
  <p>This is XSD</p>
  
  <pre><code>    &lt;xs:schema attributeFormDefault="unqualified" targetNamespace="http://www.contoso.com/books" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning" vc:minVersion="1.1"&gt;
      &lt;xs:element name="bookstore"&gt;
          &lt;xs:complexType&gt;
              &lt;xs:sequence&gt;
                  &lt;xs:element maxOccurs="unbounded" name="book"&gt;
                      &lt;xs:complexType&gt;
                          &lt;xs:sequence&gt;
                              &lt;xs:element name="title" type="xs:string" /&gt;
                              &lt;xs:element name="author"&gt;
                                  &lt;xs:complexType&gt;
                                      &lt;xs:sequence&gt;
                                          &lt;xs:element minOccurs="0" name="name" type="xs:string" /&gt;
                                          &lt;xs:element minOccurs="0" name="first-name" type="xs:string" /&gt;
                                          &lt;xs:element minOccurs="0" name="last-name" type="xs:string" /&gt;
                                      &lt;/xs:sequence&gt;
                                  &lt;/xs:complexType&gt;
                              &lt;/xs:element&gt;
                              &lt;xs:element name="p"&gt;
                                  &lt;xs:complexType&gt;
                                      &lt;xs:sequence&gt;
                                          &lt;xs:element name="price" type="xs:decimal" /&gt;
                                          &lt;xs:element name="price1" type="xs:decimal" /&gt;
                                          &lt;xs:element name="price2" type="xs:decimal" /&gt;
                                      &lt;/xs:sequence&gt;
                                      &lt;xs:assert test="price = price1 + price2"/&gt;
                                  &lt;/xs:complexType&gt;
                              &lt;/xs:element&gt;
                          &lt;/xs:sequence&gt;
                          &lt;xs:attribute name="genre" type="xs:string" use="required" /&gt;
                          &lt;xs:attribute name="publicationdate" type="xs:unsignedShort" use="required" /&gt;
                          &lt;xs:attribute name="ISBN" type="xs:string" use="required" /&gt;
                      &lt;/xs:complexType&gt;
                  &lt;/xs:element&gt;
              &lt;/xs:sequence&gt;
          &lt;/xs:complexType&gt;
      &lt;/xs:element&gt;
  &lt;/xs:schema&gt;
  </code></pre>