Unable to trap xml messages from Legacy system

hi

i was developing one prototypes which deals SAPCRM TO legacy system. Here i am create a CASE in legacy system from CRM system. Once case is created succesffuly it send response as CASE ID to XI as give below.

<?xml version="1.0" encoding="UTF-8" ?>

- <root>

- <responses>

- <response>

<caseid>73073928.00000</caseid>

</response>

</responses>

</root>

This reponse i can able to see in XI system but from XI it is not coming to SAPCRM system it is showing an error in XI saying that SYSTEM-ERROR as a Response ID.

Its an syncronous call from CRM TO LEGACY. using receiver channel as HTTP.

I did mapping testing in IR also but my only problem is my response message type is unable to pull the data of above response of legacy.

Please help what can i do to fix this problem.

regards

viswa