Can't link to Canon C300 media

I am working wth media from a Canon 5D, 7D and C300. I can do an AMA link fine to the 5D and 7D footage but not the C300 material. This is the first time I've worked with C300 footage. I have selected the 'CONTENTS' folder but also tried the card folder and other folders in the structure - nothing works. Every time I get the error message:

Unable to link to any clips at /Users/USER/Desktop/CARD ONE/CONTENTS/

My understanding is that I don't need to install an AMA plug-in - I am using MC 6.5.4.1 - but I installed Canon XF Plugin 64 for Avid Media Access 2.0.3 [Mac OS X] just in case.

Any help would be great. This has brought me to a grinding halt.

Thanks