Schedule email to go out based on CCK date field - not working for me

I have been using Rules for a number of functions on my site and I have to say, it's one of the most useful modules. Unfortunately, I don't seem to be able to get the scheduling function to work correctly, despite working on it for about a week, and I'm hoping someone can point out what I'm doing wrong.

I used these tutorials:
http://drupal.org/node/517674
http://drupal.org/node/520012

as a guide to try to send out an email to an applicant based on the "to date" field of a "Dates available" span. Here's the procedure I used to set this up yesterday:

1) Created content - a teacher application with "from" and "to" date fields for "Dates available" span.

2) Created a few dummy applications for testing with the "to" date set to today.

3) Created a ruleset: "Send email to teacher applicant {ruleset}".
- Data type: Content; Label: Content {argument}; Machine readable name: send_email_to_teach_app__content

4) Added a new rule to this ruleset: Send email to teacher applicant {rule}.

5) Added an action: System|Send a mail to an arbitrary mail address.
- Populated Recipient, Subject and Message fields.

6) Added a triggered rule: Schedule "Send email to teacher applicant {ruleset}";
Event: After saving new content

7) Added a condition: Content has type Teacher Application; Content: created content

8) Added an action: Rule scheduler: Schedule "Send email to teacher applicant {ruleset}"
- Content {argument}: created content
- Identifier: node [node:nid]
- Scheduled evaluation date: [node:field_date_available-to-date]

9) Cloned the above for updated content.
- Added a condition "Numeric comparison":
[node:field_date_available-to-date] greater than echo time();

I saw that there were 3 items matching the three dummy apps scheduled yesterday in admin/rules/rule_sets/scheduling, and I rubbed my little paws together with glee. Imagine my disappointment when no emails were waiting for me today.

Any idea what went wrong? Thanks for any light you can shed on my bewilderment.