sql server property "maximum server memory" disabled

I want to set the maximum server memory option for a SQL server, but this option is disabled for me. i have logged in through windows authentication, and logged into windows with the administrator user.

you can find this option by right click on DB server -> Select Properties -> Memory tab.

P开发者_如何学Golease see the screenshot of the properties screen in the link

Please let me know how can i change the memory option and why is it disabled for me. am i missing some permission?

Try: USE master EXEC sp_configure 'show advanced option', '1'

then stop and restart the server.