Using Add-in ExceLab 365 to calculate derivatives

Hi @Robert McCann, 

Good day. Thank you for reaching out, and I appreciate you sharing the details of your situation. 

Before we proceed, please note that this is a user-to-user community forum. As a moderator, I don’t have access to your Microsoft 365 tenant, your account, or your device to make changes directly. However, I’ll do my best to support you by sharing the appropriate resources and directing you to the right support channels. 

Since DERIVXY is a valid ExceLab 365 function, the issue is likely related to the add-in loading/registration process rather than the formula itself. 

Here are some steps you can try: 

1/ Sign in to ExceLab 365 and confirm the correct Microsoft 365 account 

• Click your profile icon and check the email address shown at the top of the account panel.  
• If the account is not correct, please select Sign Out, fully quit Excel, reopen it, and then sign in again with the correct Microsoft 365 account. 
• 

2/ Confirm that the add-in is active by testing a simple ExceLab formula 

• Please try the following formula: =QUADF(X1*X1,X1,0,1) 
• If the add-in is loading correctly, Excel should respond through ExceLab rather than treating the function name as unknown.  
• In case you receive a #VALUE! message, please click the warning icon/message, as this may simply indicate that sign-in is still required. 

3/ Refresh the add-in, then fully restart Excel 

• Please go to Tools > My Add-ins and locate ExceLab 365. Try disabling the add-in and saving the workbook.  
• Then fully quit Excel, reopen it, and enable ExceLab 365 again, as a #NAME? error can sometimes indicate that the add-in’s custom functions were not successfully registered in the current Excel session. 

4/ Clear the Office cache on Mac if the issue continues 

• If ExceLab 365 still shows #NAME?, please try clearing the Office cache on Mac. If the add-in opens a task pane, you may be able to use the task pane’s menu and select Clear Web Cache.  
• Or, if that option is not available, the cache can also be cleared manually by following steps: 
  • Quit Excel completely before clearing the cache.  
  • In Finder, use Go > Go to Folder and open: 
    ~/Library/Containers/com.Microsoft.OsfWebHost/Data/ 
  • Delete the contents of that folder.  
  • Then go to: 
    ~/Library/Containers/com.microsoft.Excel/Data/Documents/wef 
    and delete the contents of that folder as well.  
  • If either folder does not exist, check these fallback folders and delete the contents of any that are present: 
  • ~/Library/Containers/com.microsoft.Excel/Data/Library/Caches/  
  • ~/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/Microsoft/Office/16.0/Wef/ 
  • ~/Library/Containers/com.microsoft.Office365ServiceV2/Data/Caches/com.microsoft.Office365ServiceV2/ 
  • ~/Library/Containers/com.microsoft.Office365ServiceV2/Data/Library/Caches/com.microsoft.Office365ServiceV2/ 
  • Reopen Excel, open ExceLab 365 again, and test the formula once more.  
• If you use Finder to browse these folders, you may need to show hidden files, and Finder may display the container by product name such as Microsoft Excel rather than com.microsoft.Excel. 

Detailed guidance here: Clear the Office cache - Office Add-ins | Microsoft Learn 

For you references:  

• Troubleshoot custom functions - Office Add-ins | Microsoft Learn 
• ExceLab Installation Help 

This link is shared by community members for your convenience. It points to a third-party site that is not managed or verified by Microsoft. We can’t guarantee the quality, safety, or suitability of any content or software found there. Please review carefully and make sure you understand any potential risks before using it. 

5/ Contact Support   

If the issue continues, please contact your school’s IT team so they can check whether there are any account, network, or policy-related restrictions on your device or Microsoft 365 environment. 

Additionally, if needed, your IT team can also raise a support ticket with Microsoft Support through the Microsoft 365 Admin Center for deeper investigation. They have access to backend configurations and can perform a more in-depth investigation. At the very least, they can provide the most effective workaround to ensure your experience remains smooth and secure.   

In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support  

I hope this information is helpful. Should you have any further questions or need additional assistance, please feel free to share them in the comment below. I'm very happy to help.  

Thank you again for your understanding and cooperation. 

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