First you have to add a custom value with a correct date format.
The lines:
`AND CAST(wpostmeta.meta_value AS DATE) > '".date("Y-m-d H:i:s")."'
AND CAST(wpostmeta.meta_value AS DATE) < '".date("Y-m-d H:i:s", $date2)."' `
are only used to select dates between the current day and 2 months later