# \[Group Extraction] A normal screen with no issues
This **Group Extraction** help guide addresses cases where the task failed, but the screenshot shows a normal screen.
Before the guide, please first check the checklist when creating a group extraction task.
{% hint style="success" %}
**Checklist before group extraction**
*\*Images are examples for better understanding.*
The group extraction feature **operates based on the structure of the page (source page) where you first selected the data**.
Therefore, the URLs you enter afterward **must have the same structure (tab composition, layout, etc.)**to work without errors.
If you failed group extraction, first **check whether the page structure of the initially extracted page matches the URL you entered for group extraction.**
{% endhint %}
If, as above, the normal screen of the page to be extracted is displayed in the failure screenshot, please check the following.
### Case 1. The structure is different from the initially extracted page
Cause and solution
If the screen shown in the error screenshot has **a different structure from the page where you first extracted the data**(e.g., tab configuration, data location, etc.), then the system **could not relocate the initially configured data area** and an error occurred.
In this case, the error code **PartSelectionError**is very likely to be shown.
As**Checklist before group extraction**guides, **this is a typical case that occurs because the data composition can differ for each URL.**
#### **✅ Solution**
* **Choose and visit one of the URLs used for group extraction,** then perform a new extraction.
* Once the extraction is successfully completed, please create a new group based on this extraction.
* When creating a new group, in the existing group task, **\[Copy URLs]** if you click the button, you can **copy all URLs at once**from the failed group, making it easy to reconfigure.
***
### Case 2. The structure is the same from the initially extracted page
Cause and solution
If the target page in the error screenshot **is loaded normally**and the overall structure (layout, etc.) appears the same as the initially extracted page but an error still occurred, this is because **the tab where you first selected the data does not exist on the target page for group extraction.**
In this case, the error code is usually **NoMatchingTab**displayed.
#### 🧩 Why does this problem occur?
1. **When the page used as the group source does not represent the structure of the remaining URLs** (→ e.g., in a shopping mall where page 1 has many special contents like banners, ads, and recommended products, but from page 2 onward only a general product list appears, you used the entirety of page 1 as the source)
2. **When you selected an overly detailed ‘sub-tab’ during data selection** (→ e.g., you selected an area like the ‘Best Reviews’ section that does not exist on other product pages without reviews)
### **✅ Solution**
* **For this error, creating a new group extraction task is the fastest solution.** First, choose and visit one of the URLs used for group extraction, then extract the page that will become the new group source.
* **At this time, it is important to select and extract a layout that represents the other URLs to be group-extracted.** Especially for product list pages, where detailed elements like ads or MD products are mixed, **choosing the common structure from page 2 onward instead of page 1**is more stable.
*The image is an example assuming a case of group extraction for consecutive ‘list-type pages’.
* **During the process of selecting the data tab after extraction, choose a data tab covering a slightly wider area than the one used in the failed group extraction task,***(a tab that is more likely to exist in common),***which can also help.**
*Images are examples to aid understanding.
* If you select a **specific tab**that exists on the source page but not on other pages, an error may occur because a matching detailed area cannot be found on the target page for group extraction.
*The image is an example assuming a case of group extraction for similar-structured ‘detail pages’.
* *Note: By using the search bar in the results window, you can easily check which tab contains the desired data.*
* *Note: When creating a group, from the existing group task, **\[Copy URLs]** if you click the button, you can **copy all URLs at once**from the failed group, making it easy to reconfigure.*
{% hint style="success" %}
**If it is still difficult to resolve the issue even after trying the instructed methods, please contact us at** [**hello@listly.io**](mailto:hello@listly.io)**. We will help after accurately diagnosing the cause.**
{% endhint %}
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