Smile [Q] Mini sd card says Permission Denied?? Will read but not write or delete?

I am a newbie. I recently purchased a Asus Transformer Pad Tf700T from ebay that already hs been rooted with CROMI-Xenogenesis 5.4 - US ODEX. The tab is ruinning android 4.2.1

I bought a class 10 64gb mini sd card. I loaded it up with movies, pics, and music. I put the card in the tablet and it reads fine from it. But it won't let me delete anything or add anything to it? When I try I get a Permission Denied message?

Can someone please tell me how I go about fixing this.
Any help is greatly appreciated.