The "move" method is not implemented for this kind of geometry. Patch:
Index: lib/OpenLayers/Geometry/Rectangle.js
===================================================================
--- lib/OpenLayers/Geometry/Rectangle.js (revision 4930)
+++ lib/OpenLayers/Geometry/Rectangle.js (working copy)
@@ -87,7 +87,21 @@
getArea: function() {
var area = this.width * this.height;
return area;
- },
+ },
+ /**
+ * APIMethod: move
+ * Moves a rectangle
+ *
+ * Parameters:
+ * x - {Float}
+ * y - {Float}
+ */
+ move: function(x, y) {
+ this.x = this.x + x;
+ this.y = this.y + y;
+ this.clearBounds();
+ },
+
CLASS_NAME: "OpenLayers.Geometry.Rectangle"
});