realplayer 10.5 and realplayer 11

我reformat左部機before reformat我用ge realplayer 系realplayer10.5我可以用佢黎睇rmvb ge影片. after reformat我到real.com去download左realplayer11而我發現realplayer11 cannot open rmvb ge 影片
我之後delete左realplayer11 and download the old version realplayer10.5, then i find the old version can open the rmvb
點解新版ge realplayer11 cannot open rmvb 反而舊版ge 10.5得ge?can anyone tell me what is happening in my case? thank you