No feed items collected

I made two categories with existing feeds (I checked if feed URL is correct and if they have content > yes), but not a single feed item was collected to the Curated RSS Aggregator plugin from these sources. I tried “Refresh all RSS links” – but nothing happened (I tried several times). This plugin sounded very promising (at least in the paid version) but if it is not able to collect any feeds it´s useless. What could I do to make it work?