Variable names are case-independent...

rules_shipping_base.php

@@ -766,7 +766,7 @@ class ShippingRule {
 			case 'shipping': $this->shipping = $value; $this->includes_tax = False; break;
 			case 'shippingwithtax': $this->shipping = $value; $this->includes_tax = True; break;
 			case 'variable':   // Variable=... is the same as Definition=...
-			case 'definition': $this->name = $value; $this->is_definition = True; break;
+			case 'definition': $this->name = strtolower($value); $this->is_definition = True; break;
 			case 'value': $this->shipping = $value; break; // definition values are also stored in the shipping member!
 			case 'comment': break; // Completely ignore all comments!
 			case 'condition': $this->conditions[] = $value; break;