When can buyer lose earnest money?

[Albert D.]

All mighty BP experts,

Under what circumstances, would a Buyer lose his earnest money if a transaction fails?  Thanks in advance.

Background:

I'm in the middle of negotiation.  Seller is asking for serious earnest money (10% of purchase price).  Seller also asks that two weeks after contract acceptance (before closing, which we have 45 days), earnest money to be immediately turned over to the seller by the title company.