Failed to do Top-Down Distribution (TDD) in account based COPA

I did the test for top-down-distribution in account based COPA and followed three articles. It did not work.

https://launchpad.support.sap.com/#/notes/2236046

https://wiki.scn.sap.com/wiki/display/ERPFI/KE28+%28Configure+and%29+Execute+Top-Down+Distribution+of+Actual+Data

https://blogs.sap.com/2020/10/09/top-down-distribution-in-account-based-copa/

Please give me some point to do KE28 successfully.

I give my step and TDD variant Setup below:

1. I check which line item I want to distribution, and I want to distribute customer and employee.

2. Create my variance tt98. In processing instruction, customer and employee is distribution level, the other is copy value.

3. In selection criteria, I give product, company and based selection cost element.

4. Then choose value field and save variance.

5. Got the fail massege.

Thanks all.