AP Not Activating !?

[Gabe777]

Don't know what I'm doing wrong.

Took off and handflew departure following LNAV and Flight Change to altitude... FL150.

Levelled off etc. And then hit MCT on the TRP.

But AP is not activating, regardless of how I try to activate it.

Master Yaw Damper switches are ON but AP is showing Red in warning panel.

[Gabe777]

Edit: forgot that I should not use disconnect on mcp ... on yoke instead.

Been a while !