I entered all the information in the settings, including my API code.

I then used the short codes to create a page and entered the short codes below on different page.

All I get is an error: "Product Not Found" or the page displays nothing, when I use the Product list shortcode. I have confirmed that these products exist in my 1shoppingcart and I have tried numerous products. Nothing works. Please let me know how to fix this.

To fix the problem - you must build the local product table.

Go to the 1ShoppingCart settings page in your Wordpress Dashboard.

At the top of the 1SC Setting page, you will see a button labeled “Build/ReBuild” your product table.

Click on this button to retrieve the data from 1SC.  Depending upon how large your product catalog is, it may take a few seconds or it may take a few minutes to populate the locate table.