Problem installing Sandbox for Sketchup

[cheeryble]

Hi

Opened Sketchup.

Gone preferences>extensions>click Sandbox Tools.

A finder window opens with "Open" written at the top.

The drop down box near top has "Google Sketchup 8"

Then in the listing underneath is only "Sketchup" withe the Sketchup icon……but it is faded and when i click it nothing happens (Sketchup is open anyway).

The only other thing is the date to right of that line is Dec 12th 2012.

Yet I note that I have Google 8 it was installed in August 2012 and updated in December. SO seems a long time but I have previously been told I'm up to date.

Can anyone tell me where I'm wrong? I'd rely like to get Sandbox running fasts poss.

Thanks!