Convert Lead with Potential in a specific Currency

Convert Lead with Potential in a specific Currency

I'm converting leads and adding a potential through the API. 

Something like this:
</Potentials>
<row no="1">
  <option val="createPotential">true</option>
  <option val="notifyLeadOwner">true</option>
</row>
<row no="2"><FL val="Potential Name">DK Test 2</FL>
  <FL val="Closing Date">09/10/2012</FL>
  <FL val="Potential Stage">Proposal/Price Quote</FL>
  <FL val="Amount">127828.84</FL>
  <FL val="Currency">DKK</FL>
  <FL val="Probability">40</FL>
</row>
</Potentials>

This works fine, except that I'm not able to set the currency of the potential. I guess I could set the currency on the Lead before I convert it. Or I guess I could update the potential after it's created. I'm just not sure why I couldn't set it here.