Somehow in between your two posts the code got changed....
It looks like your database search code is on the page twice... did you run it multiple times on the same page without clearing the page? That might be the root of some of these problems... you may want to delete or clear the page and try again.
To simply fix the error replace:
$WADbSearch1 = new $WADbSearch1;
$WADbSearch1 = new FilterDef;
Which is what it was in your first post, but it appears there may be more issues since it really shouldn't appear twice like it is in your second code example.
The code itself, though doubled, looks correct in the first one other than the missing include file, so I'm not sure what else might have changed which is why I would probably start over.