Error of "problem with the PayPal email address supplied by the seller"

[shrd_jn]

Hi,
I am a newbie to Paypal Sandbox. I am trying to test the PayPal payment functionality of the Sandbox site via connecting it to my eCommerce application. But when my page is directed to PayPal Test Site, it gives me the following error:

"Return to Merchant

We cannot process this transaction because there is a problem with the PayPal email address supplied by the seller. Please contact the seller to resolve the problem. If this payment is for an eBay listing, you can contact the seller via the "Ask Seller a Question" link on the listing page. When you have the correct email address, payment can be made at www.paypal.com.".

I have same email account for my PayPal Sandbox Test Site login and eCommerce application. I have created one 'perconfigured' personal buyer account which has a email ID generated by the System.

Please advice.

Thanks

[shrd_jn]

Please note the eCommerce Application referred here is Konakart eCommerce Application.

Thanks !