Hi, I am implementing the intergration between my Facebook game and Paypal\'s express checkout payment service.
My website is developed in ASP.net and I
Your Order Total parameter is missing, because you're using an old version. The API request you show, and your response, do not match.
You're actually submitting version 2.3, not version 72.0.. see your API response: "VERSION=2%2e3& "
The below request and response worked for me
API Request
USER=********************
PWD=********************
SIGNATURE=********************
METHOD=SetExpressCheckout
VERSION=72.0
RETURNURL=********************
CANCELURL=********************
PAYMENTREQUEST_0_PAYMENTACTION=Sale
PAYMENTREQUEST_0_AMT=23.00
PAYMENTREQUEST_0_ITEMAMT=15.00
PAYMENTREQUEST_0_TAXAMT=5.00
PAYMENTREQUEST_0_SHIPPINGAMT=1.00
PAYMENTREQUEST_0_HANDLINGAMT=1.00
PAYMENTREQUEST_0_INSURANCEAMT=1.00
PAYMENTREQUEST_0_CURRENCYCODE=ILS
L_PAYMENTREQUEST_0_NAME0=The+name+of+product+1
L_PAYMENTREQUEST_0_NUMBER0=5543312
L_PAYMENTREQUEST_0_DESC0=The+description+of+product+1
L_PAYMENTREQUEST_0_AMT0=10&L_PAYMENTREQUEST_0_QTY0=1
L_PAYMENTREQUEST_0_NAME1=The+name+of+product+2
L_PAYMENTREQUEST_0_NUMBER1=4431234
L_PAYMENTREQUEST_0_DESC1=The+description+of+product+2
L_PAYMENTREQUEST_0_AMT1=5.00
L_PAYMENTREQUEST_0_QTY1=1.00
ALLOWNOTE=1
NOSHIPPING=1
API Response
TOKEN=EC-3UE641439J019845E
TIMESTAMP=2011-09-01T17:13:17Z
CORRELATIONID=4f7e60c2d70aa
ACK=Success
VERSION=72.0
BUILD=2085867