Index: /trunk/src/org/openstreetmap/josm/gui/mappaint/Cascade.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/mappaint/Cascade.java	(revision 6321)
+++ /trunk/src/org/openstreetmap/josm/gui/mappaint/Cascade.java	(revision 6322)
@@ -121,10 +121,9 @@
         if (o instanceof Integer)
             return new Float((Integer) o);
-        if (o instanceof String) {
+        if (o instanceof String && !((String) o).isEmpty()) {
             try {
-                float f = Float.parseFloat((String) o);
-                return f;
+                return Float.parseFloat((String) o);
             } catch (NumberFormatException e) {
-                Main.warn(e);
+                Main.debug("'"+o+"' cannot be converted to float");
             }
         }