Spend some time reviewing the options on the User Agents page, you might need to select the mobile theme from the drop-down menu and/or copy and paste the user agents list into the "Rejected user agents" section of the various caching types you have enabled.
[I don't know your setup so I can't make more specific recommendations, sorry.]
Please submit a Bug Report through the Support tab of the plugin if you continue having issues so we can get you fixed up.