Transaction Errors

I am having trouble with the checkout process, every time I try to check the form starts to process then it scrolls to the top of the screen and the woocommerce error “(Transaction Error) Email is Required” is displayed. I have turned off force ssl and I have also tried turning off allow registration on the checkout page. I have tried various browser too, in my woocommerce->orders I see the orders are coming through but the notes say sorry your transaction was declined message that I set in the authorize.net aim setting.

http://ww.wp.xz.cn/plugins/authorizenet-aim-payment-gateway-for-woocommerce/