=== modified file 'bin/addons/base/res/res_currency.py'
--- bin/addons/base/res/res_currency.py	2009-12-21 11:31:16 +0000
+++ bin/addons/base/res/res_currency.py	2010-04-07 13:57:39 +0000
@@ -78,31 +78,31 @@
         xc=self.browse(cr, uid, [from_currency_id,to_currency_id], context=context)
         from_currency = (xc[0].id == from_currency_id and xc[0]) or xc[1]
         to_currency = (xc[0].id == to_currency_id and xc[0]) or xc[1]
-        if from_currency['rate'] == 0 or to_currency['rate'] == 0:
-            date = context.get('date', time.strftime('%Y-%m-%d'))
-            if from_currency['rate'] == 0:
-                code = from_currency.code
-            else:
-                code = to_currency.code
-            raise osv.except_osv(_('Error'), _('No rate found \n' \
-                    'for the currency: %s \n' \
-                    'at the date: %s') % (code, date))
-        rate = to_currency.rate/from_currency.rate
-        if account and (account.currency_mode=='average') and account.currency_id:
-            q = self.pool.get('account.move.line')._query_get(cr, uid, context=context)
-            cr.execute('select sum(debit-credit),sum(amount_currency) from account_move_line l ' \
-              'where l.currency_id=%s and l.account_id=%s and '+q, (account.currency_id.id,account.id,))
-            tot1,tot2 = cr.fetchone()
-            if tot2 and not account_invert:
-                rate = float(tot1)/float(tot2)
-            elif tot1 and account_invert:
-                rate = float(tot2)/float(tot1)
         if to_currency_id==from_currency_id:
             if round:
                 return self.round(cr, uid, to_currency, from_amount)
             else:
                 return from_amount
         else:
+            if from_currency['rate'] == 0 or to_currency['rate'] == 0:
+                date = context.get('date', time.strftime('%Y-%m-%d'))
+                if from_currency['rate'] == 0:
+                    code = from_currency.code
+                else:
+                    code = to_currency.code
+                raise osv.except_osv(_('Error'), _('No rate found \n' \
+                        'for the currency: %s \n' \
+                        'at the date: %s') % (code, date))
+            rate = to_currency.rate/from_currency.rate
+            if account and (account.currency_mode=='average') and account.currency_id:
+                q = self.pool.get('account.move.line')._query_get(cr, uid, context=context)
+                cr.execute('select sum(debit-credit),sum(amount_currency) from account_move_line l ' \
+                  'where l.currency_id=%s and l.account_id=%s and '+q, (account.currency_id.id,account.id,))
+                tot1,tot2 = cr.fetchone()
+                if tot2 and not account_invert:
+                    rate = float(tot1)/float(tot2)
+                elif tot1 and account_invert:
+                    rate = float(tot2)/float(tot1)
             if round:
                 return self.round(cr, uid, to_currency, from_amount * rate)
             else: