(This issues impacts purchases made before Feb 10, ’10)
Issue: For products with single variants, the Sold Out message does not show when the inventory is 0.
Fix:
1. Open product.liquid
2. Find the section of code that looks like this:

{% if product.variants.size > 1 %}
<div id="product-select">
	<select id="product-variants" name="id">
	{% for variant in product.variants %}
		<option value="{{ variant.id }}">{{ variant.title }} - {{ variant.price | money }}</option>
	{% endfor %}
	</select>
</div>
{% else %}
	<input type="hidden" name="id" value="{{ product.variants.first.id }}" />
{% endif %}

and replace it with this:
<div id="product-select">
	<select id="product-variants" name="id">
	{% for variant in product.variants %}
		<option value="{{ variant.id }}">{{ variant.title }} - {{ variant.price | money }}</option>
	{% endfor %}
	</select>
</div>

In a nusthell, we are removing the if test and leaving the select in place for all variants.

3. Scroll to the bottom of product.liquid and replace the following code:

// initialize multi selector for product
{% if product.variants.size > 1 %}
	new Shopify.OptionSelectors("product-variants", {product: {{ product | json }}, onVariantSelected: selectCallback});
{% endif %}

with:
// initialize multi selector for product
new Shopify.OptionSelectors("product-variants", {product: {{ product | json }}, onVariantSelected: selectCallback});
{% if product.variants.size == 1 %}
	$("#product-select").hide();
{% endif %}

Not comfortable making these changes? We can make them for you. Please Contact Us and we will arrange for the changes to be made on your site free of charge.