diff -ur userpoints.orig/userpoints_basic.module userpoints/userpoints_basic.module
--- userpoints.orig/userpoints_basic.module	2007-02-14 00:35:59.236837300 +0100
+++ userpoints/userpoints_basic.module	2007-02-16 03:27:15.964091900 +0100
@@ -131,6 +131,9 @@
     case 'invite':
       $points = variable_get(USERPOINTS_INVITE_INVITE, 0);
       break;
+    case 'cancel':
+      $points = -variable_get(USERPOINTS_INVITE_INVITE, 0);
+      break;
     case 'escalate':
       $points = variable_get(USERPOINTS_INVITE_REGISTER, 0);
       $op = 'register';