when I try to turn

HI when I try to turn on GZIP compression I get message

"gzip is not working properly:

- Your server may not have the "deflate" module enabled (mod_deflate for Apache, ngx_http_gzip_module for NGINX)
- Another plugin may be interfering with the configuration
"
I've turned off & deleted any other plugins that were doing any minifying or compression or similar and tried disabling then reactivating the Hummingbird plugin but with no success