Getting Error in SAP NetWeaver gateway client when choosing Entitysets

Dear SAP Friends,

We have created the service for sale order with 2 entities (SOHeader and SO Item) and after executing the URL we got the output and  its worked fine for last 4 months and upto last 3 days back also(10.06.2015) .

yesterday we are getting the error while choosing entity sets (SOheader and SOItem) ,

Error :RFC Error: Syntax error in program /IWBEP/CL_MGW_ABS_DATA========CP

Without selecting entity -its working fine,

the interface /IWBEP/IF_MGW_APPL_SRV_RUNTIME have been used for sale order header and item classes and this interface worked fine between  front end and backend system earlier.

Note: There is no changes happen in ABAP methods and  we have verified the versions for Sale order class and its methods .

also we have checked with Basis team , they ensured that no package upgrades or installations  happened for our system for last 2 weeks.

Please guide me  to fix this error message.

Error message:

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

Regards,

Kannan