Hi Felipe,
If it does not work even after setting the change document as suggested by Vinod, you may have to create Change document object in SCDO workbench.
There is a very detailed article in wiki SCN about to how create change document objects.
http://wiki.sdn.sap.com/wiki/display/ABAP/Maintaining+Change+Log+for+Database+Tables
Let us know if you have any further questions.
Regards,
Sanjay