Multiline Equation won't center and align on equals sign

I have a multiline equation which I wish to align on the '=' and center the equation block on the page.

I have selected align on '=' and center as a group, however the equation group becomes left justified on the page (and aligned on the =). No matter what I do I cannot get it to concurrently center the group on the page and also align on the '='.

Does anyone know what setting at what level would cause this type of behavior?

(I'm using MS Word 2011 on OS X 10.8)

Very late to the party, but in the Microsoft Equation Editor in OneNote (not Word for some reason), you can type the & symbol before whatever you wish to align by. You can even align different symbols so long as the & comes before it. You must start the next equation/line with Shift+Enter, including the line beyond the last line you wish to align. You just delete the extra line at the end. I haven't found a way around that small limitation, but it's minor since you can remove it.

Not sure if it's a bug or not but in Microsoft Word 2011 on OSX 10.8, but only choosing justification > 'centre as group' will result in the equation group becoming left justified and aligned on '='.

In order to get the expected behaviour one must also go to Word > 'Preferences' > 'Equations' > 'Display Math' and tick the checkbox for 'Use the following settings for math on its own line' then set justification to 'centered as group'.