Uninstall doesn't work after silient installation?

[Yiping]

We have an installation that has three install sets,
let's say A, B and C. A is default install set.
We set the INSTALLER_UI=silent
and make the silent installation of A, B and C.
But the uninstall doesn't work after silent installation for B and C.
What could be the reasons?
Thanks a lot.

[rmilbrath]

I have 5 msm files that all work correctly if ran individually. If we combine them into a single project, then they fail randomly.

Also, we marked them as silent, then not all child functions execute.

Any ideas?