[MonetDB-users] Mapi - mal

Hello, I would like to get the oid of a stored uri using the Mapi library. The mal commands that need to be executed are: tokenizer.open("rdf"); id := tokenizer.locate("http://uri"); io.print(); tokenizer.close(); I tried to run the following program ...tokenizer.open("rdf");... ... if ((hdl = mapi_query(dbh, "tokenizer.locate(\"http://uri\")")) == NULL || mapi_error(dbh) != MOK)       die(dbh, hdl); if (mapi_close_handle(hdl) != MOK)       die(dbh, hdl); while (mapi_fetch_row(hdl))       result=mapi_fetch_field(hdl, 0); ... ...tokenizer.close();... .. but I get the following error Mapi.mx:5141: mapi_fetch_row: Assertion `(hdl)->mid' failed. Could you tell me how can I solve this problem? Kind regards, Petros