IDOC_ERROR_PARSE_FAILURE: An IDocIllegalTypeException occurred while parsing IDocXML:state=READING_SEGMENT_STARTTAG

Hello Experts,

We are getting a strange issue while trying to post IDOC into ECC through PO 7.31 Single Stack.

We are having a custom segment in IDOC with a single field.If we don't create that segment in PO,i.e. if we don't map this segment the IDOC is getting posted.But if we map the custom segment(setting SEGMENT=1),we are getting error "com.sap.engine.interfaces.messaging.api.exception.MessagingException: com.sap.conn.idoc.IDocParseException: (7) IDOC_ERROR_PARSE_FAILURE: An IDocIllegalTypeException occurred while parsing IDocXML for type <*IDOC_NAME*>:

state=READING_SEGMENT_STARTTAG, charPosition=834, lineNumber=1, columnNumber=835".

I have gone through other discussion in scn related to this exception,but they are not similar to our problem.

Please suggest.

Regards,

Suman