Hi ,
So it is clear that the drop target is not accepting.
In the link https://scn.sap.com/thread/1619267 Thomas stated that " Drag and Drop with ALV is not possible until NetWeaver 7.02. If you are on NetWeaver 7.01 you can do drag and drop with the regular table UI element, but not with the ALV. "
I assume you were in 7.02 or higher ,
Check the below links
http://scn.sap.com/thread/1580661
https://scn.sap.com/thread/1619267
Component : WDR_TEST_DRAG_AND_DROP
Regards,
Karthi M