HTTP 500 Error during parsing of SOAP header

Hi

I am trying to pick up a file and send it to Sap XI 3.0 , but I get this error :

Sending binary message "9aebdb18-de08-3904-b53e-e5288ff90fd5" type "application/xml" to Integration Engine... (message size: 7 bytes, URL: "http://xi:8004/sap/xi/engine?type=entry"

ERROR: Finished sending to Integration Engine with error "com.sap.aii.messaging.net.TransportException: HTTP 500 Error during parsing of SOAP header

http-Response:

content-type: text/xml

content-length: 963

content-id: <soap-72E83B43EDD76260E1000000AC101E43@sap.com>

soapaction: 'http://sap.com/xi/XI/Message/30'

server: SAP Web Application Server (1.0;640)

http://schemas.xmlsoap.org/soap/envelope/">

<SOAP:Header>

</SOAP:Header>

<SOAP:Body>

SOAP:Client Error" target="_blank"> http://schemas.xmlsoap.org/soap/envelope/"> SOAP:Client Error during parsing of SOAP header http://sap.com/xi/XI/Message/30 xmlns:SAP=" http://sap.com/xi/XI/Message/30" xmlns:SOAP=" http://schemas.xmlsoap.org/soap/envelope/" SOAP:mustUnderstand="1"> XIProtocol ITEM_MISSING /@versionMajor ST: ST_XMS_MSGHDR30_MAIN Attribute 'versionMajor' expected XML tag /@versionMajor missing in SOAP message header (SAP XI Extension)

<b>Attribute 'versionMajor' expected</b>

</SAP:Stack></SAP:Error></detail></SOAP:Fault>

</SOAP:Body>

</SOAP:Envelope>

Can someone tell me what is going on?

what does it mean "Attribute 'versionMajor' expected" ?

Thanks a lot.