I just tested the formula in Sesame Seasons sample database.  Works fine, no problem.

Here is the formula I used:
{ ShipDate > @Date - @Dow(@Date) AND ShipDate <= @Date - @Dow(@Date) +7 }
I modified it to use ShipDate vs. Sale_Date.
I went to the Retrieve screen.  Had to press F6 to expand the ShipDate element, pasted in the code, closed the expanded window, pressed F1o to retrieve.  Got the records I expected.

Two items to look at:
1.  Do you have an element named Sale_Date?  Change the name in the formula to the Date Element Name that you want to use.
2.  Do you actually have records for This Week in your database?  May need to change some dates to confirm testing OK.

Edited  ......
I just looked at the article, did not read it, but saw what Alec was doing.  I just saved the same spec above, then called the spec, worked OK.

Here are my steps:
1.  Go to Retrieve Screen
2.  Expand the Date Element, paste in the formula, close the expanded window.
3.  Open Spec Manager.
4.  Load the Retrieve Spec
5.  Click on tab to Save Spec
6.  Enter name "This Week's Shipments" (without the quotes)
7.  Beneath the name, enter "Shipments for today and next 6 days" (without the quotes)
8.  Click on button to Save
9.  Close Spec Manager.

Tested by clearing specs on Retrieve screen pressing F3
Open Spec Manager, loaded spec named "This Week's Shipments"
Saw the formula in Shipped Date, pressed F10, and correct records came up.

What are you doing?
What results are you seeing?

Format should not matter as long as it is a real DATE field.

Is the element BOUND to a DATE field? 
If it is a text field, it will not work. 

Are you using the Field Name, and not the Label/Element Name?

I am guessing that the 1/9/2007 you provided is just an example of format.  But that date may be this year, but it definiely is not THIS WEEK.

How many records do you get if you go to the date field and put this in as a spec?
>{@Date-7}  This should be last week's records unless you have future ship dates entered.

The formula in the article is using THIS WEEK, starting with a relative Yesterday, for the next 7 days.
Example for 09/03/2007
{ ShipDate > @Date - @Dow(@Date) AND ShipDate <= @Date - @Dow(@Date) +7 } =
{ ShipDate > 9/3/07 -  1                   AND ShipDate <= 9/3/07 - 1                    +7 }   =
{ ShipDate > 9/2/07                         AND ShipDate <= 9/9/07 } =
THIS WEEK.

I have the following retirve specs, I have changed the shipdate to Date Completed0

This Week
{ Date Completed0 > @Date - @Dow(@Date) AND Date Completed0 <= @Date - @Dow(@Date) +7 }

This Year
{ @Year(Date Completed0) = @Year(@Date) }

Last Year
{ @Year(Date Completed0) = @Year(@Date) -1 }

When i run it i get "sorry, no recrods match date range"

Thanks once again.


drastixnz

@drastixnz: Are all three failing?

Also, make sure you are using the underlying field names, NOT the element names. Retrieve Spec programming is one of the only places where you need the field name itself.