I Cannot get Keynote to Zoom In

I have decided to use keynote for 'Wire Framing' but as I am used to using photoshop for this I have altered some keyboard shortcuts (some of Keynotes are ridiculous). I have run into a problem though where in the edit mode Keynote won't Zoom In with 'CMD' + '=' ( + ) and even disabling this shortcut Keynote won't zoom in. Pressing the keyboard shortcut kets just gives me the error sound.

Any ideas here?

Thanks.