Yeah it's a pain sometimes. A lot of sites that host freebies don't require that uploaders post versioning info. (They really should though.) So if you're still running older software, you can often hit this roadblock. Unlike Bryce or some other apps, Carrara doesn't make versioning obvious in the file extensions or descriptions.

Many will argue that you should upgrade. Sometimes budget or older hardware prevents this. Not to mention that sometimes the new bugs that show up also make the effort to upgrade less compelling than whatever the new features may make it out to be. (Whether that's the case for Carrara, who knows? But some other software, I've been happy to stick with what has worked. That whole "If it ain't broke..." adage.)

In additon to versioning - some shaders also require the use of add-ons. Plugins by Inagoni or DCG for instance. Anyone uploading shaders using those should mention it though.

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Barbequed Pixels?

Your friendly neighborhood Wings3D nut.
Also feel free to browse my freebies at ShareCG.
There might be something worth downloading.