Short sale Question - Urgent

[Tammy Braz]

I just put an offer on a short sale property.  I put down a $1,000 deposit and offered the asking price (The SF home had gone down several times and there were multiple offers).  The seller accepted my offer. And now the bank has to approve.  My agent wants me to get an appraisal and put down a larger deposit before the bank approves the short sale.  Is this the normal procedure for a short sale? I don't want my deposit tied up, if the bank isn't going to approve the deal.  Please advise.