Unable to read the payload from the message object

Hi,

We are using XI to get an a file as outbound (File Adapter) and then send it to R/3 as IDoc inbound (IDoc Adapter). When we do "test configuration" from the Integration Directory we get an error message in "Interface Determination & Mapping" Step "Unable to read the payload from the message object". We did test the mapping from the Integration Repository and the test was successful. Did anyone had the same issue before? Please advice... Thanks in advance.