Assembly Build, error QBS cannot build this assembly item because one of its components has a cost that is less than zero." Costs are in. How do I fix this please?

Good work for checking the items' costs, Cherylwupsllc. This QuickBooks unexpected behavior is often caused by corrupted data.

We'll run the verify/rebuild tool to detect the data damage. I'll show you how:

1. Click File.
2. Go to Utilities, then choose Verify Data.
3. If QuickBooks detected no problems, there's no further action needed. If you receive a message, "Your data has lost integrity", the file is damaged. Just continue to Rebuild Data to correct the problem.
4. When you Rebuild Data, you'll receive a message to back up your company file, just click OK. The utility starts as soon as the back up is finished.
5. Click OK when you get the message "Rebuild has completed".
6. Run Verify Data again to check for remaining data damage.

Once done, create the inventory assembly item again.

Let me add the article on how you can track the products you build using inventory items. 

You can keep us updated after trying these steps. Just leave a comment and we'll answer you as soon as we can. 

Thank you Kristine Mae, I greatly appreciate your assistance with this issue!!

Yesterday, I encountered the same issue. After running Verify and Rebuild, no change was observed. I then duplicated the affected assembly and added components one by one to identify which item caused the zero-balance problem. Through this process, I discovered that the issue was caused by previous inventory adjustments made to that component’s account.

Solution
I created a new account for the affected component and re-entered it into the assembly. This resolved the problem.