shortcut of making vim windows/panels equally in height

I was reading the byte of vim. Here is a problem that I encountered.

I am using vim in macosx. (command line not GUI)

In the book, "Want to make the windows 'equal' in height again? press ctrl-w =" I have tried that, but it does not working. And, it made some sound (which I believe it indicates that th开发者_如何学运维ere is an error)

In addition, when I have looked at the mac vim help page about window, I did found this command. I tried it again---still does not work in the command line mode, but it did works in GUI mode (MacVim)

Does anyone have any ideas to solve that? Thanks a lot!

You wouldn't happen to be pressing Ctrl-WCtrl-=, would you?

I tried Ctrl-W= in Vim in a Terminal, and it worked. Ctrl-WCtrl-= didn't work in the terminal, but it did in MacVim.