ActiveMerchant throws an invalid transaction error

I am trying to incorporate ExpressCheckout with Paypal using Active
Merchant and when I click on the express checkout button it takes me to
the paypal site and gives me an error that says Invalid transaction
error please use the ......

I notice that the error log does not generate a token at the time of
sending the request and it looks something like this

So i feel that the error lies there but I may be wrong.

I have a setup a paypal account and a buyer seller accounts are in

My Controller looks like this

def express
    cart = find_cart
    price = cart.get_price_in_cents
    response= EXPRESS_GATEWAY.setup_purchase(price,
{:ip=>request.remote_ip, :return_url=>new_orders_url,
    redirect_to EXPRESS_GATEWAY.redirect_url_for(response.token)

I would appreciate any kind of help with this.