WP e-commerce set default variation?

Trying to set a default variation. The parts optionally have some additional painted patterns on them. If they don’t select any options I want to show the standard one (without additional painted pattern). As it is now they select the basic color they get a notice “Combination of product variants is not available” because they haven’t selected an optional pattern. I want to avoid this error by setting “no optional pattern” as the default. Can’t figure out is this is possible or where to set it. The initial value now is “please select” rather than one of the variations.