> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://help.optis.me/sitemap.xml
> Use this file to discover available pages before exploring further.
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# Why does the cart add the default variant instead of the selected one?

1. [OPTIS Color Swatch](/swatch)
2. [Variant Display](/swatch/variant-display)
3. [Common questions](/swatch/variant-display/common-questions)

# 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:**

1. **Go to Online Store → Themes → Edit theme**

![Online Store Themes section with the Edit theme button](https://storage.crisp.chat/users/helpdesk/website/-/2/9/4/4/294423ae57be5000/135311a6-a20d-48bc-b2b9-0a7013_mqbjrl.png)

2. **Open the Product template**

![Product template selected in the theme editor](https://storage.crisp.chat/users/helpdesk/website/-/a/3/6/2/a362d3151b477000/6e604b20-4ab2-42a8-8b57-4aa685_1toxxjy.png)

3. In the **Product information** section:

* Add the **theme’s Variant Picker**
* Add the **OPTIS app block** as well

![Adding the OPTIS app block to the product template](https://storage.crisp.chat/users/helpdesk/website/-/4/1/4/f/414f5d4f82d66c00/9d3c90cc-6c38-4e9c-9d79-ed34c4_1x8b36y.png)

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.