Software Deployment

Hello
Why components are not reinstalled if I use a majorUpgrade?
I have several setups, where not all components are reinstalled if I use a majorUpgrade & the Action 'RemoveExistingProducts' in the MajorUpgrade is locatet after InstallValidate. The not reinstalled components are unversioned and have newer or equal dates in the newer package. 'CostFinalize' in MajorUpgrade notify Disallowing installation of component: {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX} since the same component with higher versioned keyfile exists, but these files have'nt a version!!
If I move the 'RemoveExistingProducts' before CostInitialize all works fine. But I would like a answer for this effect. It's a error in Windows Installer?
I've found many of links for the same scenario:
http://community.macrovision.com/archive/index.php?t-116526.html
http://itninja.com/question/excellent-links-for-sus-information8&mpage=1&key=僮
http://community.macrovision.com/showthread.php?t=162356
...but no really answer.
Did you can help me?