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Make sure Java Runtime is installed. Adobe apps use it but it isn't a default install in Lion. Read this link from Adobe.

http://kb2.adobe.com/cps/909/cpsid_90908.html


Dale

Java Runtime has been installed for months now, but I just checked it to be sure; it's definitely installed. I've never had trouble installing any other Adobe applications. I was even able to install the new dng converter from Adobe. But the new ACR refuses to install, and until it does, I can't get Lightroom 4 and Photoshop CS5 to play nicely together.
 
If anyone else has this problem, try this:

1) Go to /Library/Application Support/Adobe/Plug-Ins/CS5/FileFormats

2) Remove whatever version of ACR is in there

3) Restart

4) Re-run the 6.7 installer​

That finally got it to work for me.
 
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