When I press my MUTE button the unit goes into standby, and understood from the manual the mute button will activate keyboard lock, am I wrong ?, thanks

it puts mine to standby when I hold it for a moment... but doesn't do anything with caps on my BB.

I'm guessing that was a mistake in the subject since the body of the OP mentions "keyboard lock" instead of "caps lock"...

Holding mute activates standby. In standby, the BB will not accept input from the keyboard.

Holding mute goes into standby. The keyboard is effectively locked, but it's not the same. In keyboard lock, the screen will come on to tell you to unlock it. In standby it doesn't. I prefer the standby mode much better. It will still receive calls and messages and bluetooth connections.