diff -ur original/uc_store/uc_store.admin.inc patched/uc_store/uc_store.admin.inc
--- original/uc_store/uc_store.admin.inc	2011-03-11 18:13:32.000000000 +0200
+++ patched/uc_store/uc_store.admin.inc	2011-04-06 23:11:31.000000000 +0300
@@ -218,7 +218,7 @@
       $query->condition('o.' . $address . '_first_name', $first_name, 'LIKE');
     }
     if ($last_name !== '0' && $last_name !== '%') {
-      $query->condition('o.' . $address . '_last_name', $first_name, 'LIKE');
+      $query->condition('o.' . $address . '_last_name', $last_name, 'LIKE');
     }
     if ($email !== '0' && $email !== '%') {
       $query->addField('o', 'primary_email');