Apologies for the inconvenience cause!
Please refer to following link for installing and placing TWAIN plugin: TWAIN is not installed with Photoshop Elements 11 .
Enjoy Photoshop Elements,
The legacy TWAIN plug-in usually works only with 32bit apps. PSE15 is a 64 bit application so it is unlikely to be compatible.
You may need to use the software that came with your scanner, to get photos onto your computer and then import into Elements 15.
If you still have an older 32 bit version of PSE you can keep it installed and it will happily work side by side with PSE15.
My apologies for such a slow reply. I had to find my old disc for PSE10. I have re-installed this and it works well with PSE15 as you said. I scan in PSE10, save to desktop and then open in PSE15 to edit.
What a shame that Adobe have a new programme with so many bells and whistles but we have to use an older version to get a decent scan. I wonder if there is any chance of a scanner update in the future?