Hi
I had the same problem with addresses not being fully qualified and then not being found.
I used the District field to enter the coordinates in and changed the code to use that field only.
Add: $geostuff = "$obj->district";
to estateagent.php and change the line:
$gmap->addMarkerByAddress($geostuff , 'This is a title', '<b>xxx</b>'

;
hope this helps