Hi Khan,
You may need oss note as per your bw version,. if your on bw7.3 then this note would be useful.
https://service.sap.com/sap/support/notes/1698685
Another note: 1130965
At Data source, extraction tab, you may have character set(try 1100), need change and keep on try at particular number you may succeed your load.
Thanks
