Error while sending EDI message through HTTP adapter

Hi,

I have a biztalk orchestration bound to a request response port. It receives a 270 message and sends back 271 message. I use HTTP adapter where in I gave /HttpEliInq/BTSHTTPReceive.dll. It also has “suspend failed requests” checked. I use the EdiReceive and EdiSend pipelines. I have a test web application that sends the 270 message and expects the 271 message back. But it is timing out after sometime. Meanwhile, after sending the 270 message, i see there is one suspended instance in the BizTalk Message box. When i open the suspended instance, it shows three messages.
 
 1) 271 message with the message type “http://schemas.microsoft.com/BizTalk/EDI/X12/2006#X12_00401_271“. The message details show that this is the body part
 2) NACK message with no message type in the suspended(not resumable) state. The message is as below.
  <SOAP:Envelope xmlns:SOAP=”http://schemas.xmlsoap.org/soap/envelope/” SOAP:encodingStyle=”http://schemas.xmlsoap.org/soap/encoding/”><SOAP:Body><SOAP:Fault><faultcode>Microsoft BizTalk Server Negative Acknowledgment </faultcode><faultstring>An error occurred while processing the message, refer to the details section for more information </faultstring><faultactor>/HttpEliInq/BTSHTTPReceive.dll</faultactor><detail><ns0:NACK Type=”NACK” xmlns:ns0=”http://schema.microsoft.com/BizTalk/2003/NACKMessage.xsd”><NAckID&gt;{EE1A58D0-21AE-4E39-9D71-69F693FB3D4B}</NAckID><ErrorCode>0xc0c016aa</ErrorCode><ErrorCategory>0</ErrorCategory><ErrorDescription>There was a failure executing the response(send) pipeline: “Microsoft.BizTalk.Edi.DefaultPipelines.EdiSend, Microsoft.BizTalk.Edi.EdiPipelines, Version=3.0.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35” Source: “EDI assembler” Receive Port: “Receive270271Port” URI: “/HttpEliInq/BTSHTTPReceive.dll” Reason: Root element is missing. </ErrorDescription></ns0:NACK></detail></SOAP:Fault></SOAP:Body></SOAP:Envelope>
 3) Another message with no message type and is empty with the message status consumed and the service status suspended(not resumable). The message details show that this is the body.
 

I am thinking since the body is empty, it generates the NACK message.
 
where am I going wrong? Please help me with this issue.

Thanks,
Bizzy