i just tried it to overwrite, but no results.
What do you mean with "overwrite" ??
i still can´t see anything, except the ground textures but slightly.
Since you said the FSX Addon Manager reports the scenery beign active, then it's active, and the Addon Manager is running so, this doesn't have anything to do with it.
If you don't see the scenery with the Addon Manager running, then it's surely something related to your scenery.cfg that was already corrupted/had a syntax errror before running the installer. But in this case, you should have seen a warning message from the installer, that the file hasn't been touched because it was already wrong, so the installation didn't continued, and that's why you don't see any scenery, because no files were copied if the installation aborted for this reason.
As I've said, if this is the case, you should have seen an error message when installing.
i must say, that i use a different drive for fsx. fs9 is drive d and fsx is drive e. does it matter?
No, it doesn't, unless you installed FSX on one drive, then manually moved it to the other drive after the installation, which would create an huge mess (basically, nothing will probably work)