Gzip Commpression Issues

Hi There

I am trying to optimise my site using Hummingbird and I am running up against some issues.

The primary issue is that the Gzip is not/will not configure correctly, and is therefor hindering the site performance. It is activated but I states that 'gzip is not working properly'. I have a dedicated cloud server so have full control but am unsure what the issue may be as well as how I could resolve it.

If you could advise asap I would be ver grateful.

Alex