if (!spConfig) {
return;
}

with it.

if ((typeof spConfig == ‘undefined’) || !spConfig) {
return;
}

spConfig is not defined

can you help ?
i have in my store simple and configurable products…

// simulate firing a DOM event
if (typeof fireEvent !== ‘function’) {
document.fireEvent = document.createEventObject ? // IE
function(element, event) {
var evt = document.createEventObject();
return element.fireEvent(‘on’ + event, evt);
} : // FX
function(element, event) {
var evt = document.createEvent(‘HTMLEvents’);
evt.initEvent(event, true, true); // event type, bubbling, cancelable
return !element.dispatchEvent(evt);
};
}

// preselect the 1st option of the 1st-maxPreselectedAttributeOptionCount’th configurable attribute
document.maxPreselectedAttributeOptionCount = 2;
Event.observe(window, ‘load’, function() {
if (!spConfig) {
return;
}
for (var i = 0; i < Math.min(maxPreselectedAttributeOptionCount, spConfig.settings.length); ++i) {
var attr = spConfig.settings[i];
attr.selectedIndex = 1;
Event.observe(attr, 'change', Prototype.emptyFunction);
fireEvent(attr, 'change');
}
});