Just to follow this up, after viewing Robert's files the problem is that the field type used to store the date is a "timestamp" data type which stores the date as 'YYYY-MM-DD HH:MM:SS' this means that you cannot use a single date i.e. MM/DD/YYYY to do a find orders placed on this date using the standard DataAssist search behaviour.
The answer was to add another column to the database to store just the date and use this for the search.
This involved updating his current orders table with this command:
alter table orders add column DateInsert date DEFAULT NULL;
UPDATE orders p, orders pp
SET pp.DateInsert = DATE(p.OrderDate)
WHERE pp.OrderID = p.OrderID;
which will add the DateInsert column and populate it with the date calculated from the OrderDate timestamp field.
Then the Add Cart Summary Server Behaviour needs to be updated so that the date is added to the new column when a new order is placed.