I'm using the Report Wizart to import an XML file and I'm getting the message "Unable to smart link unlinked tables". Why is this happening?

I am also including the schema file which indicates primary and foreign keys.



<?xml version="1.0" standalone="yes"?>
<NewDataSet>
<Student>
    <StudentID>0</StudentID>
    <Name>A0</Name>
</Student>
<Student>
    <StudentID>1</StudentID>
    <Name>A1</Name>
</Student>
<Student>
    <StudentID>2</StudentID>
    <Name>A2</Name>
</Student>
<Student>
    <StudentID>3</StudentID>
    <Name>A3</Name>
</Student>
<Mark>
    <StudentID>0</StudentID>
    <Mark>10</Mark>
</Mark>
<Mark>
    <StudentID>1</StudentID>
    <Mark>11</Mark>
</Mark>
<Mark>
    <StudentID>2</StudentID>
    <Mark>12</Mark>
</Mark>
<Mark>
    <StudentID>3</StudentID>
    <Mark>13</Mark>
</Mark>
</NewDataSet>


and Schema is :

<?xml version="1.0" standalone="yes"?>
<xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
<xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:UseCurrentLocale="true">
    <xs:complexType>
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element name="Student">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="StudentID" type="xs:string" />
              <xs:element name="Name" type="xs:string" minOccurs="0" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="Mark">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="StudentID" type="xs:string" minOccurs="0" />
              <xs:element name="Mark" type="xs:string" minOccurs="0" />
              <xs:element name="MarkID" type="xs:string" minOccurs="0" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:choice>
    </xs:complexType>
    <xs:unique name="Constraint1" msdata:PrimaryKey="true">
      <xs:selector xpath=".//Student" />
      <xs:field xpath="StudentID" />
    </xs:unique>
    <xs:keyref name="ReportPhone" refer="Constraint1">
      <xs:selector xpath=".//Mark" />
      <xs:field xpath="StudentID" />
    </xs:keyref>
</xs:element>
</xs:schema>


even i remove link and create link manually but i cant display my report :(
why is that incorrect ? what am i doing wrong ?


please help me ,