TWAIN Plugin won't work

Question

Hi all,
I've tried everything for this and it still doesn't work.
I've downloaded both of these files from this link;
http://www.adobe.com/support/downloads/detail.jsp?ftpID=4965
I've gone into Applications - Photoshop CS5 - Plug-ins - Import/ Export and pasted TWAIN there manually. I've also double clicked the Optional_Automate.zxp and TWAIN Plugin.zxp files and installed them within the Extension Manager. TWAIN exists within the Extension Manager and has a tick to show it's installed and it is in my plug-ins folder, yet it does not work.
When I double click TWAIN Photoshop opens and gives me this error;
"Could not complete request because Photoshop does not recongise this type of file"
I'm using an EPSON Stylus SX100 and it has a scanner on it. My drivers for the printer are updated. Photoshop CS5 is at the latest version (12.0.2)
Why won't TWAIN work?

Answer 1

When you double click the TWAIN.plugin file (actually, bundle), the Finder thinks you want Photoshop to open it as an image document, and of course it's not. That's where the error message is coming from.
It sounds like you have the TWAIN plugin in the proper place for Photoshop. You can watch the Photoshop splash screen during startup to see if it shows a task of "Building TWAIN menu items...", which indicates it has found the plugin.
You will also need to make sure you have installed the appropriate TWAIN driver for your scanner. Note that this may be a separate install from the other software that came with your scanner, which (probably) does not use TWAIN. You can check your installed TWAIN drivers by looking in the folder: /Library/Image Capture/TWAIN Data Sources (note that this is the top level Library folder, not the one in your user directory), you should see one or more things in there, typically with the name of your scanner and an extension of ".ds".
Finally, as Chris noted, there are very few TWAIN drivers that have been updated for 64-bit; most TWAIN drivers are 32-bit only. If you launch Photoshop in 64-bit mode (which is the default), the File > Import menu will only show TWAIN drivers that are 64-bit, and will omit any that are 32-bit only. If that's the case for your scanner, you can restart Photoshop in 32-bit mode to allow you to scan.
Hope this helps,
Paul