Forcing Install of 64-bit Excel Add-ins
With the wrong bit of the add-ins installed, you may be seeing this error message upon opening Excel:
When installing the PowerOLAP Client, it detects whether or not your installed version of Microsoft Office is 32-bit or 64-bit. It does this by looking at a key in the registry at this location (replace 15.0 with whatever version of Office you have installed):
If the 'Bitness' key is set to 'x64' then PowerOLAP will install the 64-bit Excel add-ins. If it is set to 'x86' or this key does not exist it will install the 32-bit Excel add-ins. (Note: the Bitness key only exists in the Outlook folder. This key shows the bitness of the entirety of Microsoft Office, not just Outlook.)
To force the install of the 64-bit add-ins you simply need to create the 'Bitness' registry key (string value) at the above path and set it's value to 'x64.'