Hi,
Seems like your data source initialized with selections already.
If you wand to do reinit(with same selections) then first we need to delete the existing init other wise you can do the init with other selections.
So go to your init info pack at BW server, RSA1.
open your info pack, menu scheduler-->init options for source system-->here you will see existing init, select and delete it. That will delete your init.
Cross check at source system RSA7. your data source will won't be there.
After that you can create or use old info pack and do the init as you need.
Thanks