[Hummingbird Pro] Enabling Hummingbird Stops Point of Sale from Working

I have just installed Hummingbird Pro on my site for caching. However our Point of Sale will no longer load when the plug-in is activated. I tried adding the web address for the POS to the no-cache rules but it still will not load. I have turned off all minification and CSS/Javascript optimization as well as page caching and it still will not load. Once I disable the plugin it works fine though. Can you please suggest other areas I can look at to see why this will no longer work? Thanks!