Cartesian product?

I recently received this error message: Error -395 "The where clause contains an outer cartesian product" - What does that mean? The book isn't exactly verbose when it says: "Check the syntax" The select that caused this is: select presult.batchno, presult.smpleno, smple.nature, smple.ordr, presult.pmethno, presult.methno, presult.anateno, analyte.sort, smple.descrip, smple.sdate, smple.stime, batch.wonum, smple.smpleid1, smple.smpleid2, analyte.descrip, presult.result, presult.unts, presult.dl,presult.dlpow from presult, outer ( smple, batch, outer analyte) where presult.anateno = 103 and (presult.guyno = 0 or presult.guyno = 84) and presult.released = 0 and batch.batchno = presult.batchno and smple.batchno = presult.batchno and smple.smpleno = presult.smpleno and analyte.anateno = presult.anateno order by batch.wonum, smple.ordr, analyte.sort Any comments? I'm not sure what's wrong.