I've got 33 for the sum of the digits of the middle row and 37 for the sum of the digits of 3dn but I'm slightly confused as to where I have gone wrong. I'd be very grateful if somebody would be willing to engage in email correspondence as I can't say any more without giving away quite a lot of information which I know to be correct, possibly ruining the puzzle for others.
My email is mcdonnell . bc @ gmail . com
(please ignore the spaces in the email address, I had to insert them as it would not let me post any links due to me being a new member)