Index: uc_discounts_role.module
===================================================================
--- uc_discounts_role.module	(revision 2775)
+++ uc_discounts_role.module	(working copy)
@@ -24,7 +24,11 @@
 
 function uc_discounts_role_check($condition, $total_price, $cart) {
   global $user;
-  return isset($user->roles[$condition->item_id]);
+  if ($condition->op == '=') {
+    return isset($user->roles[$condition->item_id]);
+  } else {
+    return !isset($user->roles[$condition->item_id]);
+  }
 }
 
 function uc_discounts_role_item_field() {