Hello Krishna,
The error you are finding in CG50 may have more information in WWI monitor.
Generate the report again and check if it goes on error in CG50, if yes, go to WWI Monitor (CG5Z) and look for the report you generated. Double-click and there will be the generation log.
The error found here will provide you much more information, not really much , but at least more 
Please let us know what you find.
Best regards,
Raphael