CO-PA extractor

After following BuildingBlock for CO-PA (creating DS in OLTP in KEB0, and so on) I went to RSA3 to test the extractor and I get an error message: "Errors occurred during the extraction Message no. RJ012". I googled it and nothing appeared.

In the Log generated for the extraction test, I find an entry: "No source could be found to answer the search query".

Has anybody experienced something like this when implementing COPA ?

Kind Regards,

Santiago