Another PapPal Sandbox question

Hi,

I have reviewed existing topics regarding PayPal Sandbox problems. It seems simple enough: "If you want to use the sandbox, you just need to configure your sandbox account (a buyer and a seller), set the seller account of your sandbox account in the paypal plugin options and change the URL in these options to use the sandbox URL"

I apologize in advance, but I must be a little challenged in my aptitude for this. I have established buyer and seller accounts within PayPal Sandbox. I have tried configuring the PayPal Payment Plugin within HikaShop with both the real account email and the Sandbox seller account email and pointed the URL to www.sandbox.paypal.com/cgi-bin/webscr . Either way, when I go to my website to test a transaction, I get to a screen that tells me I am being redirected to the PayPal page. The next screen that appears says "Please login to use the PayPal Sandbox features". I saw the topic that said to login to the Sandbox first. I have tried that with the real account email (same result), but PayPal Sandbox will not allow me to login with the Sandbox seller account credentials. I would love it if you could point out the error in my approach so that my next message could be "You're right - it works great!".

Thanks for all you do - I am highly impressed with your product.