I developed a project with WINCC TIA PORTAL PRO 15.1, in a stand alone version. Now my customer ask to me to make the system redundant by installing 2 servers instead of the stand alone station. I read the manuals, and took all the necessary steps to set up the servers. I have included servers in the redundancy options of the project. I created the engineering station as the manual, and the simatic Shell sees the servers. During the download phase the system asks me for the destination folder, which I find on server 1, the system performs the compiling but then the following message appears:

The current project contains a reduoundant server configuration. Loading to another device is not possible.

I don't understand what it means, and I can't find explanations anywhere

can someone help me ?

thanks