This error occurs when you are using a 32-bit Normal Server as a source server when performing a remote install to a 64-bit target machine. You cannot have a mixed source and target. If your target is a 64-bit machine, you need to choose a 64-bit source, such as a Normal Server already installed on x64 machine.
If you have multiple x64 machines that need to be installed remotely, choose one x64 server as a source server. If this is the first x64 server, you need to install SPNT in it using setup.exe from the ServerProtect installer.
Once you have your first x64 machine with ServerProtect, you can then perform remote installation to the rest of the x64 servers using this first server as the source.