Why do I install the latest version of MacOS and Xcode fail?

I would like to upgrade the MacOS, Xcode and the iOS simulator to latest version.

However, the MacBook Pro Mid 2009 cannot upgrade to the latest as the message.

"This version of macOS10.13.3 cannot be install on this computer."

The Current MacOS is 10.11.6

The Current Xcode is version 7.0.1(7A1001)