Required attribute 'ref' of parent element

I am trying to validate a XMLSchema and have som problems (I'm using XMLSPY
v.4.0.1). When I validate the attached xsd file, I get the following error
message:

"Required attribute 'ref' of parent element 'group' expected before first
child element".

This error is detected within the sequence of <!-- bankkonto.kontonumre -->
.

<?xml version="1.0" encoding="ISO-8859-1"?>
<schema targetNamespace="http://www.storebrand.no/xmltjenester/1.0"
xmlns:tj="http://www.storebrand.no/xmltjenester/1.0" xmlns:konto="
http://www.storebrand.no/xml/1.0/bankkonto" xmlns:felles="
http://www.storebrand.no/xml/1.0/felles" xmlns="
http://www.w3.org/2001/XMLSchema">
  <include schemaLocation="C:\TEMP\xmlstorebrand\fellestjeneste.xsd"/>
  <import namespace="http://www.storebrand.no/xml/1.0/bankkonto"
schemaLocation="C:\TEMP\xmlstorebrand\bankkonto.xsd"/>
  <!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - -->
  <!--                           Deltjenester input Bankkonto
-->
  <!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - -->
  <!-- bankkonto.kontonumre -->
  <complexType name="bankkonto.kontonumre.input">
    <choice>
      <element name="deltjenestereferanse" type="tj:tjenestereferanseType
"/>
      <group>
        <sequence>
           <element name="kontrollparametre" type="tj:kontrollparametreType
" minOccurs="0"/>
           <element name="fn" type="felles:fn"/>
        </sequence>
      </group>
    </choice>
  </complexType>
  <!-- bankkonto.kontoinformasjon -->
  <complexType name="bankkonto.kontoinformasjon.input">
    <choice>
      <element name="deltjenestereferanse" type="tj:tjenestereferanseType
"/>
      <group>
        <sequence>
           <element name="kontrollparametre" type="tj:kontrollparametreType
" minOccurs="0"/>
           <element name="fn" type="felles:fn"/>
           <element name="kontonummer" type="konto:kontonummer"/>
        </sequence>
      </group>
    </choice>
  </complexType>
  <!-- bankkonto.kontoutskrift -->
  <complexType name="bankkonto.kontoutskrift.input">
    <choice>
      <element name="deltjenestereferanse" type="tj:tjenestereferanseType
"/>
      <group>
        <sequence>
           <element name="kontrollparametre" type="tj:kontrollparametreType
" minOccurs="0"/>
           <element name="fn" type="felles:fn"/>
           <element name="kontonummer" type="konto:kontonummer"/>
           <element name="periode" type="gYearMonth" minOccurs="0"/>
        </sequence>
      </group>
    </choice>
  </complexType>
  <!-- bankkonto.transaksjoner -->
  <complexType name="bankkonto.transaksjoner.input">
    <choice>
      <element name="deltjenestereferanse" type="tj:tjenestereferanseType
"/>
      <group>
        <sequence>
           <element name="kontrollparametre" type="tj:kontrollparametreType
" minOccurs="0"/>
           <element name="fn" type="felles:fn"/>
           <element name="kontonummer" type="konto:kontonummer"/>
           <choice minOccurs="0">
             <group>
               <element name="fra-og-med" type="date"/>
             </group>
             <group>
               <sequence>
                 <element name="fra-og-med" type="date"/>
                 <element name="til-og-med" type="date"/>
               </sequence>
             </group>
             <group>
               <sequence>
                 <element name="max-antall">
                   <simpleType>
                     <restriction base="integer">
                       <minInclusive value="0"/>
                     </restriction>
                   </simpleType>
                 </element>
               </sequence>
             </group>
           </choice>
        </sequence>
      </group>
    </choice>
  </complexType>
  <!-- bankkonto.engasjement -->
  <complexType name="bankkonto.engasjement.input">
    <choice>
      <element name="deltjenestereferanse" type="tj:tjenestereferanseType
"/>
      <group>
        <sequence>
           <element name="kontrollparametre" type="tj:kontrollparametreType
" minOccurs="0"/>
           <element name="fn" type="felles:fn"/>
        </sequence>
      </group>
    </choice>
  </complexType>
</schema>

(See attached file: bankkontoInput.xsd)

Espen Dietrichs