Error while determining root tag of XML: BOM / charset detection failed

Dear experts,

Scenario:

A sender JMS adapter picks file from a specified queue, and sends to PI for conversion, the file is xml file already, so no need to add any modules to JMS adapter.

However the message failed in PI as error below:

< SAP:Category > XIServer </ SAP:Category >

< SAP:Code area =" IF_DETERMINATION " > CX_ID_PLSRV </ SAP:Code >

< SAP:P1 > No interface determination found for outbound interface urn:sysco.com:sysco:tms:sc:logistics.FreightCost_Out: Error while determining root tag of XML: BOM / charset detection failed </ SAP:P1 >

I have tried to find any clues online, and suggested that to check whether any charset description is mentioned in the source message.

But the first line of the xml picked has mentioned the encoding type-- UTF-8 :

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

Then what is the issue about, much appreciated anyone can provide some inputs.

Thanks a lot!