Is below not a valid date format, I only get 'walk the dog' with no date when it's added?
Walk the Dog <date Jan 18, 2014 11:00AM>
Please try removing "date" from that syntax, and let me know if it still does not work for you.
Didn't work, the task gets added with the date as part of the todo, not as the assigned date.
Please try to keep the date, but if it has a time, you must add either @ or at before the time, for example, these two should work:
Walk the Dog <date Jan 18, 2014 @ 11:00AM>
Walk the Dog <date Jan 18, 2014 at 11:00AM>
If they won't, then it could be caused by the fact that you're trying to set a date into the past.