Hi Angie,
thank you for your replay. I was afraid that my post was too lengthy to be answered. I checked again the pre-requisites on the servers that have failed the installation:
1) IIS Management Console is installed on all servers - I can see the Transform Manager with the Queues in the IIS Management Console
2) .NET 3.5.1 is also installed on all servers, on some servers there is .NET 4.5 Mutiple Target and .NET 4.5.1 Preview Version installed. One issue: how can I check if it is .NET 3.5.1 SP1 and not just .NET 3.5.1 (Installation of .NET 3.5.1 was via Server Roles --> IIS Role features or via Server Role --> Application Server)
3) I am logged in as Administrator, the installation of the IIS TM msi package was as administrator and - among the various trials - I also set the Credentials of the IIS TM Host to an administrator account.
As I said in my first post: installation was done on some virtual Win 2008 servers within 15 minutes - on the other I tried for some days...
Kind regards & thank you for your efforts
Stephan