Property didn't appraise

[Carlos Rodrigues]

I'm selling a a new construction property for a client and property didn't appraise and the seller is very upset.  The property appraised at $505k. Theres a $40k difference.  We're under contract at $545k.  The comps seem to be at $515k though.  Are there anything other ways to get the $40k or at least part of it, besides having the Buyer dish out $40k?  Anything I could say to convince the Buyer possibly?  Seller wants to cancel contract.