XML : WSO2 ESB can not get response from rest API

I have a proxy that put data into parameters ({uri.var.parameter}) and Call a rest api for post parameters in that. The response for this api is like it:

  <ResultSet count="1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">     <Result>        <id>126</id>        <contact_type>Individual</contact_type>         .         .         .  </Result>  </ResultSet>    

When I call this api with parameters in the soapui, I can see the above response, But when I call it by WSO2 ESB 4.9.0 I receive an error : First Element must contain the local name, Envelope , but found ResultSet My request was posted to the api but wso2 esb can not parse the response. When I put property OUT_ONLY=true in synapse, my request went successfully but obviously I don't receive any response. When I checked content_type in response header in SoapUI, it is :text/xml;charset=UTF8 I found this post and added content_type:text/xml in both messageFomatter and messageBuilder in axis2 configure file, but I still receive same error. Could you please provide me your sollution. Thanks