“Add to cart” adds the full amount not the deposit

Trying to get the plugin to work. I’ve added and activated the plugin. Within the Product set up I’ve enabled the Deposit option in the Product Data area and tried both a fixed amount and a percentage amount for the deposit value.

Whatever I try, when I get to the cart, the full amount is there and not the deposit.

I’m sure I’m doing something stupid but can’t see what.

Can you point me in the right direction?

Thanks.

P.S. This is only a test product. The real products have values in excess of 6,000 so having a deposit mechanism is important.

The page I need help with: [log in to see the link]