Thank you for your post.
Your script steps are fine. I don't have an immediate answer why this is happening, but I ran into something similar to this years ago where one record would be found, even though the criteria was not met/checked.
Go into Layout Mode and add another instance of the Checkbox field. However, do not format it as a checkbox. Leave it as a standard field, and size it for three or more lines. Then, go into Browse. You will see each of your checkbox entries on a separate line. My guess is that the record in question actually has the word "Sold" or "Returned" in the field somewhere. This could have been caused by changing one of the values in the value list or adding a value list after data was entered.
Please keep me posted! If this is not the answer, I would like to look at the file. I have sent you a private message (top of this page - right side - X Messages) with instructions where to send the file just in case.
Thank you TSGal, that solution worked! Thanks a lot.