This error occurs because the the path to the Scribe.NavAdapter.NasHook.dll file could not be found by the MSI installer.
The installer is using a hard coded path: C:\Program Files (x86)\Microsoft Dynamics NAV\\Application Server...
In many cases the file exists in the C:\Program Files (x86)\Microsoft Dynamics NAV\60\Application Server... folder

The resolution is to COPY the Application Server folder to C:\Program Files (x86)\Microsoft Dynamics NAV folder
Run the installation and then delete the copied Application Server 

Notice path to Scribe.NavAdapter.NasHook.dll

Typical AX 2009 NAS folder 

 

This error may occur when installing the when installing the ScribeAdapterForMicrosoftDynamicsNAV2009NAS.msi on the NAS server