Nvidia Geforce Experience can't optimize Rust

So i see rust finally got his way to Nvidia Geforce Experience

http://postimg.org/image/vb0o3v81h/

http://postimg.org/image/vb0o3v81h/

Problem is when i’m clicking the ‘Optimize’ button i get this messege:

http://postimg.org/image/g3s9985yt/

link: http://postimg.org/image/g3s9985yt/
Anyone know how to fix that?