can't install the 3d Ikea kitchen planner

I can't install the 3D Kitchen Planner on my new MacBookPro OS X 10.7. It worked perfectly on my old iMac!

When dowloaded, I try to drag the icon (blank sheet of paper) into the folder (internet plug-ins) to install, but it comes up with a box saying "the item np2020 player Ikea plugin cant be moved because 'internet plugins cant be modified".

Ive tried downloading on Firefox & Safari, but both say the same.

What am I doing wrong?