Missing CSS

I’m using v3.2.2 of hyper cache. I’m using it with a plugin called “oik nivo slider”:

https://ww.wp.xz.cn/plugins/oik-nivo-slider/

I have found that when hyper cache is enabled, the CSS files necessary for oik-nivo-slider are missing. I examined the plugin; it looks like it’s just using the standard wp_enqueue_style code; I’m not sure what would be unique about it.

Using the plugin on completely vanilla settings (haven’t changed anything).

Suggestions/ideas?

thanks!
sam

https://ww.wp.xz.cn/plugins/hyper-cache/