PayPal doesn't recognize store as valid Merchant

-- url of the page with the problem -- : www.m2820.com/store/store/
-- HikaShop version -- : 2.6.1
-- Joomla version -- : 2.5.20
-- PHP version -- : 5.6.17

If you enter your address in the shopping cart ( www.m2820.com/store/store ), then enter you credit card, it tries to take you paypal, but instead you get the error message: "Some required information is missing or incorrect. Please correct the fields below and try again. Error: Invalid Merchant or Merchant doesn't exist!"

This was working yesterday, and as far as I know, nothing has changed. I just all the sudden saw several emails come through where the same person was trying to make a purchase. So, I went to give it a try and saw this happening. Thoughts? I have not changed any of the settings in HikaShop or PayPal that I can remember.

Hi,

Can you please provide details about your Paypal plugin configuration ?
Because the message "Invalid Merchant or Merchant doesn't exist" is not provide by any HikaShop plugin but it is a message which can be display by Paypal advanced plugin.

And Paypal advanced is really different than Paypal classic.

Regards,

I think I figured it out. Thank you though.