XML Schema Validation Error. It appears to be inline with the schema

I am getting an error while validating my xml document against its schema. Please help.

Below is the XML document I am trying to validate.

<?xml version="1.0" encoding="utf-8"?>
<QuestionForm xmlns:xsi="http://ift.tt/ra1lAU" xmlns:xsd="http://ift.tt/tphNwY" xmlns="http://ift.tt/1oLVbcb">
  <Overview>
    <Text>This is overview</Text>
  </Overview>
  <Question>
    <QuestionIdentifier>nextmove</QuestionIdentifier>
    <DisplayName>Display Name</DisplayName>
    <IsRequired>true</IsRequired>
    <QuestionContent>
      <Text>The Main Question will go here?</Text>
    </QuestionContent>
    <AnswerSpecification>
      <FreeTextAnswer>
        <Constraints>
          <IsNumeric minValue="0" maxValue="9999" />
          <Length minLength="0" maxLength="4" />
        </Constraints>
        <NumberOfLinesSuggestion>1</NumberOfLinesSuggestion>
      </FreeTextAnswer>
    </AnswerSpecification>
  </Question>
</QuestionForm>

Here is the link for XML Schema document.

[http://ift.tt/1n48zTk]

Here is the error message

Unhandled Exception: Amazon.WebServices.MechanicalTurk.Exceptions.ParseErrorException: There was an error parsing the XML question or answer data in your request.  Pl
ease make sure the data is well-formed and validates against the appropriate schema. Details: cvc-complex-type.2.4.a: Invalid content was found starting with element
'QuestionContent'. One of '{"http://ift.tt/1oLVbcb":QuestionIdentifier}' is expected. (14084243
91173 s)
   at Amazon.WebServices.MechanicalTurk.MTurkClient.ProcessErrors(ErrorsError[] errors, Object ret, OperationRequest opsReq)
   at Amazon.WebServices.MechanicalTurk.MTurkClient.SendRequest(Object req)
   at Amazon.WebServices.MechanicalTurk.MTurkClient.CreateHIT(CreateHITRequest request)


  [1]: http://ift.tt/1oLVbcb