Cautionary Tale No.1: I have a 1930's death cert which states deceased was interred at Northern Suburbs - but no record there. Eventually I looked up her funeral notice in Sydney Morning Herald (at National Library in Canberra - but believe volunteers at Ryerson Index will do so for a donation perhaps) and discovered that, in fact, she had been buried at Waverley Cemetery. Last minute change of plans? Funeral directors had a busy day? Who knows.
Cautionary Tale No.2: Great-uncle Kavanagh who had been repat patient for several years at Randwick Hospital was interred at Botany Cemetery. No record - until someone got the bright idea to look up Cavanagh. And there he was, with a war service headstone under the wrong name!
So, look for other spellings, other cemeteries. And try to find a death or funeral notice in the papers. Sydney Morning Herald was the paper of choice for such notices back then.
Cheers
Barbara