I see two problems-
$this->table_name = $wpdb->prefix . "b99_pf";
$sql = "CREATE TABLE " . $table_name . " (
$table_name
will be undefined, should be $this->table_name
and in your query:
cat tinytext default NOT NULL
I don’t think it’ll like that default
in there.
EDIT – to answer your debug question- xdebug, xdebug and netbeans