Shopp 1.1.5 was recently released with a lovely bug that makes the Authorize.net payment module fail. This particular bug effects JavaScript validation of the credit card field. Since the JavaScript source is compressed, it’s very difficult to debug, so I’m not exactly sure why it’s failing. Here is a quick workaround to get you back in action.
I’m going to assume you’re using theme templates, if not, do that and then come back. First, open “checkout.php” and look for this:
<?php if (shopp('checkout','card-required')): ?>
Just above that, add a couple of new lines and then paste in the following:
<!-- a hack to make credit card validation work? --> <input type="hidden" name="paymethod" value="credit-card" />
<!-- a hack to make credit card validation work? -->
<input type="hidden" name="paymethod" value="credit-card" />
<?php if (shopp('checkout','card-required')): ?>
Start a fresh session on your site and see test it out.