Welcome aboard to the Community space, @sbm1.

I'm here to help and ensure you'll be able to complete your build assembly in QuickBooks Desktop (QBDT).

Let's perform some troubleshooting steps to isolate and fix this issue. I suggest creating a sample company file and build your assembly from there. Let me guide you how.

1. Go to the File menu.
2. Click New company.
3. Select Express Start.
4. Follow the onscreen steps to finish the setup.

You can also check out this article for more details: Create a QuickBooks Desktop Company File. 

If you're able to build assembly with ease, I suggest running the Verify Rebuild tool. This scans, your company file for minor data issues and fixes it right away. If the issue persists, I suggest running a clean install. This fixes issues that keep you from opening your file and a few other situations.

Once everything is all set, please feel free to utilize these links for guidance in effectively managing your inventories: 

• Set up Advanced Inventory QBDT 
• Adjust your inventory quantity or value in QuickBooks Desktop 

I'll be around to help you out whenever you have other questions about assembly or with your QuickBooks. Keep me in the loop by leaving the details in your reply. Keep safe and happy holidays! 

I can build other assemblies just not this particular one.  I tried your suggestion to create a sample company file but there is not an express option to create a company file.  Just the option to do a new company or new company from existing file.  I tried the new company still no express option, takes me to a setup that would be a completely blank company so no way to test the assembly.

In searching some of the forums, this seems to be a Quickbooks issue  INV-19434.  Did this ever get resolved?

Now I get this error message, I've verified that nothing has a cost less than zero.

Assembly Build, error QBS cannot build this assembly item because one of its components has a cost that is less than zero." 

Hello there, sbm1.

Thank you for adding more information about your concern, especially the investigation number. This will give us a better overview of what’s happening to your inventory (build assembly).

You’re correct. The issue you’re experiencing when building assembly is already reported to our engineers. The current investigation is still open and being worked on with utmost urgency.

Since you’re getting an error after running the workaround steps, I recommend contacting our Technical Support Team. One of our specialists will collect personal data to add your name to the list of affected users. You’ll receive email updates once more information is available about the issue.

Here’s how:

1. Open your company file and go to the Help icon at the top menu bar to select QuickBooks Desktop Help F1.
2. Scroll down to the bottom of the window and click the Contact us link.
3. In the Contact Us screen, enter a brief description about the issue in the Tell us more about your question box. For example, unable to build assembly.
4. Press the Search menu and pick Call us to speak with an agent or Message Us to chat with one of our agents.
5. Provide this number to speed up the process: INV-19434.

Let me share this article for additional resources: Fix negative inventory issues in QuickBooks Desktop. From there, you’ll learn how to resolve when an item has no average cost, tips to prevent negative inventory, and solutions to fix it.

Additionally, the following link contains resources that will guide you on how to efficiently handle any inventory activities: QuickBooks self-help articles.

Stay in touch if you have additional questions on how to manage your assembly items. I’ll get back to help and make sure this is taken care of for you.