Dreamweaver CC 2017 Link Error

Hi everybody,

I'm hoping some can shed some light on this because I'm at a complete loss. Ok, so I have a .css file which when I link to it Dreamweaver is finding the actual file. However,  when I'm in the 'code' view, a red-dot appears next to the file to indicate that it's missing. The files window can see the file is there in the correct location. Yet, Dreamweaver complains that file is missing in the 'code'.

Any ideas?

Thanks in advance