loobs... realistic prices part 2

Hi Loobs... just though I would update you with what happened with the house I was telling you about in Willetton WA which is on the market for $635000 and is a 4 * 2 home. Anyways I followed your advice and put a offer on of $499000 on Saturday and the real estate agent just got up and walked out. As he was getting in his car I ran out and said obviously you are not happy with that so can I amend it to $515000... he then drove out the driveway! Thus not sure if your technique is correct there and doesnt seem like they are desperate to sell. Can you advise the next step I should take then?? Thanks in advance