This soap message gave me: common.exception.ApiException: Must send a concrete entity type

This soap message gave me: common.exception.ApiException: Must send a concrete entity type." any help

- + <SOAP-ENV:Envelope
    xmlnsSOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
    xmlnsxsd="http://www.w3.org/2001/XMLSchema"
    xmlnsxsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlnsSOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
    xmlnsns4="urn:enterprise.soap.sforce.com">
   - + <SOAP-ENV:Header">

      - + <ns4:SessionHeader SOAP-ENV:actor="http://schemas.xmlsoap.org/soap/actor/next" SOAP-ENV:mustUnderstand="0"">

         - + <ns4:sessionId">
2B5EBcdbCQyx100n_l.Tc9IJxB58ycqeQpNjxYxLn.WHHWcAzBCOJiKQ326vI.rVa48ZzIdoYXXueiqB7dpq4jteaH1xyGi1ns4:sessionId>
        </ns4:SessionHeader">

     </SOAP-ENV:Header">

   - + <SOAP-ENV:Body">

      - + <ns4:update">

         - + <ns4:sObjects">

            - + <ns4:type>Account_Environment_Profile__c</ns4:type">
            - + <ns4:Id>a0130000000Ib75AAC</ns4:Id">

            - + <ns4pportunity__c">
00630000001p257</ns4pportunity__c">
           </ns4:sObjects">

        </ns4:update">

     </SOAP-ENV:Body">

</SOAP-ENV:Envelope">