CMS Made Simple Forums

Since the site I'm working on only has six products, I'm using direct details calls, e.g.:
{Products action="details" productid="3"}

However, even when I am using the default template, the add-to-cart form is not being rendered.

CMS and all modules seem to be up to date, and I'm using promotions (but haven't defined any yet).
The products have options.

Any pointers on how to troubleshoot this?

Note that in the default detail template the code is commented by asterisks:
Change to: Further, you MUST enter a unique SKU per product/product option. Those are 'hidden' on the 'Advanced' tab of product items.