IE11 is a "rolling train wreck". I had it for a brief period with my Windows 8.1 preview (which has now expired, thank God - what a pile of garbage that was).
The loons in Redmond DELIBERATELY screwed up the "User-Agent Strings" in 11 to make it difficult, if not impossible for sites to identify (http://blogs.msdn.com/b/ieinternals/archive/2013/09/21/internet-explorer-11-user-agent-str ing-ua-string-sniffing-compatibility-with-gecko-webkit.aspx). It shows up as Gecko (Firefox) on some, unidentified browser on all the rest.
Well, when the pages can't recognize the browser, they don't recognize any of the plugins, like Flash Player. So far, Microsoft has made NO indication that they have any plan to fix it soon.
Microsoft's recommendation is to use Compatibility View for affected pages, and "pretend" you're using an different browser. Trouble with that is it has seen limited success at best, and you have to individually enable it for EVERY page that has problems.
I'm not big on "pretending" so I recommend actually using another browser.
ANY of those will work where IE11 won't, with the Flash Player Plug-in (For all other browsers), and Chrome doesn't even need that because it has its own Flash Player plugin built in.
Thanks Mike, it resolved my problem