Hello Daniel
Thanks for the fast Feedback!
The Problem I
had was, that the Setup of my application dosn't check the prerequirements on install procedure.
Example:
- I have a pure Windows XP (without Framework 4.0)
- Running my Setup on that machine dosn't detect that there is no Framework 4.0 on the machine.
- It installes my Application without to install Framework 4.0 before.
If I build my Setup with "Build All", it works as before

I dosn't have changed anything in the Installer Project, but select "Build All" ??!!
If I will found more details about this behaviour I will let you now.
Best regards
Horst