Index: sites/all/modules/signup_scheduler/signup_scheduler.install
===================================================================
--- sites/all/modules/signup_scheduler/signup_scheduler.install	(revision 2524)
+++ sites/all/modules/signup_scheduler/signup_scheduler.install	(working copy)
@@ -39,4 +39,15 @@
   while ($variable = db_fetch_object($variables)) {
     variable_del($variable->name);
   }
+}
+
+/**
+ * Implementation of hook_update()
+ * Set the weight of the signup_scheduler module to be heavier of
+ * that of the signup module, so it always runs after.
+ */
+function signup_scheduler_update_1() {
+  $weight = db_result(db_query("SELECT weight FROM {system} WHERE name = 'signup'"));
+  $new_weight = $weight + 1;
+  return array(update_sql("UPDATE {system} SET weight = ". $new_weight ." WHERE name = 'signup_scheduler' LIMIT 1"));
 }
\ No newline at end of file