Adding mask problem

Following tutorial.
Have a person maked out. they are black with white bg on duplicate channel. Totorial says to make bg layer regular layer. The click add mask button and the mask magically appears next to layer. All I get is a empty white mask next to the 0 layer. and a layer 0 mask above the duplicate channel. so I'm a bit lost.

Have a person maked out. they are black with white bg on duplicate channel.

Have that selected, with marching ants first. If it is an alpha channel, or a layer and the object is isolated in that channel or on that layer, control click and that will select the subject.

Then you can click the Add Mask button and your mask will appear.

thanks Yrbk,
that may be it, maybe the ants we not active. thanks.