paypal not accepting payments at checkout

I have installed WooCommerce, and I am trying to test my website’s shopping cart using PayPal (the only available option), but my PayPal account information is being rejected. I know the account is fine, given that I can get into it directly through PayPal.com. Everytime I enter the information, I keep getting “Please check your email address and password and try again”. http://swaggertag.com/shop

Your help is much appreciated.

http://wordpress.org/extend/plugins/woocommerce/