[OpenLayers-Users] 'undefined' at vertices while editing vector layer

[Alex Dean]

When I define my own styling for a vector layer, I see 'undefined' at  
the vertices while editing a feature.

Screenshot of feature when I'm not editing it : http://skitch.com/alexdean/dwe1i/without-editing
Screenshot of feature while editing: http://skitch.com/alexdean/dwe14/with-editing

Using Firebug/Firefox, I can see the following SVG for one vertex.
<circle id="OpenLayers.Geometry.Point_146" cx="827.6666666759318"  
cy="79.09283407817736" r="6" fill="undefined" fill-opacity="0.5"  
stroke="undefined" stroke-opacity="0.8" stroke-width="4" stroke- 
linecap="round" stroke-linejoin="round" stroke-dasharray="none"/>

I see 'undefined' is the value use for 'fill' and 'stroke', so I  
imagine one of these may be the problem.  I can't figure out what keys  
I need to define in my style objects to resolve this problem.  Can  
someone help?

This is how I've defined the layer:

wfs = new OpenLayers.Layer.Vector("Regions", {
   styleMap: new OpenLayers.StyleMap( {
     'default':{
       label: "${name}",
       fillColor: "${color}",
       fillOpacity: 0.5,
       strokeColor: "${color}",
       strokeOpacity: 0.8,
       strokeWidth: 4,
       pointRadius: 6,
       fontColor: "#000000",
       fontSize: "24px",
       fontFamily: "Courier New, monospace",
       fontWeight: "bold"
     }
   })
});

The edit control is defined as follows:

var edit = new OpenLayers.Control.ModifyFeature(wfs, {
   title: "Edit Existing Region",
   displayClass: "olControlModifyFeature"
});

As you can see in the screenshots, the 'color' attribute (eg "$ 
{color}") has been set for the feature in question and is rendered  
correctly when I'm not editing the feature.  The 'undefined' text only  
appears when I edit the feature using an instance of  
OpenLayers.Control.ModifyFeature.

thanks,
alex