Hi Gustavo,
I am assuming that you have changed the value of SELECTION = 'X' in the table ROOSFIELD for making the field as selection enabled.
I am sorry to break it to you that it will not work because in the extraction FM for this datasource the extraction is done on table KEKO and below selection criteria is hard coded in FM.
So even if you make other fields as selection possible it will never work.
Unless SAP releases a patch/Note to modify the FM SREP_COPC_PCP_10 and make it more field selection enabled.
I think it is better to use KADAT if you want to use selection criteria and then manipulate your data in BW further using KADKY.
Please let me know if there are any questions.
Thanks
Amit