Focus Area Select Not Working

Hi. Updated my work PC to Photoshop CC 2014. Select/Focus Area is shown in drop down menu. I can open the Focus Area panel, but it does nothing to the image regardless of what setting I select in the sliders.

When I place the cursor over the image with this panel open, I get a circle with a slash through it, seemingly to indicate that this function is not available on this image. Image opened is DNG format from Lightroom CC.

I updated my graphics driver and checked that PS is using the GPU in the Preferences panel. The 'Use Graphics processor' is ticked.

System is a PC running Windows 7 professional. Core i5-2310 CPU 4cores. 4GB RAM (total).

I know the RAM size is small and I will be getting another 8GB or so soon. Can this be the cause of the problem?

Any help would be appreciated.

Regards

Steve

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