Guild Challenge Error

Hi,
We are a new guild (Down Under) trying to start a Guild Challenge. We currently have 25 members.
Each time we try, an Error note appears saying "You must have 10 members before playing a Guild Challenge"
I've sent a support ticket, with the reply "Try clearing your cache and try again"
How do you clear cache?
Does anyone know what might have happened or could assist?
Cheers,
69ers (AUS) - Right hand of Down Under
It depends on your browser. But for most of them you click on the browser menu ( Chrome, Safari, etc.) and then go to Settings. From there you can clear browser history, cookies, and the cache. On some browsers you go to Privacy. It would be best to Google your specific browser; ex: "How do I clear cache on Chrome". It also lets you know what you should and should not clear.
Good Luck with your guild!
Cheers TopTown... The 10th member that joins the guild needs to be in for a minimum of 48hrs before starting a GC.