> For the complete documentation index, see [llms.txt](https://docs.optis.me/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.optis.me/swatch/variant-display/common-questions/why-does-the-cart-add-the-default-variant-instead-of-the-selected-one.md).
# Why does the cart add the default variant instead of the selected one?
This usually happens when the **theme’s variant picker is not properly enabled or connected**.
Our app works **on top of Shopify’s native variant configuration**, not independently. This means the theme’s variant picker must be active so Shopify knows which variant is currently selected.
**How to fix this:**
{% stepper %}
{% step %}
**Go to Online Store → Themes → Edit theme**
{% endstep %}
{% step %}
**Open the Product template**
{% endstep %}
{% step %}
In the **Product information** section:
* Add the **theme’s Variant Picker**
* Add the **OPTIS app block** as well
{% endstep %}
{% endstepper %}
Once the variant picker is enabled, the selected variant will:
* Stay in sync when customers change variants
* Be correctly added to cart instead of reverting to the default variant
👉 **Important notes**:
* OPTIS **restyles and enhances Shopify variants** - it does **not** create a separate variant system.
* The theme’s variant picker **must remain enabled** for image switching to work properly.
* If you see **both the theme variants and OPTIS swatches showing at the same time**, this is usually a theme conflict. In that case, please **contact our support team** and we’ll help resolve it.
After enabling the variant picker, kindly double-check the product page. If the issue still persists, feel free to reach out - we’re happy to assist further.