I have read other posts on the very same subject but I didn't get solution. Below code is working code and I have used this code multiple times but don't know what I am doing wrong right now,
Below is $padata:
METHOD=SetExpressCheckout
RETURNURL=My return link
CANCELURL=My cancel link
PAYMENTREQUEST_0_PAYMENTACTION=SALE
L_PAYMENTREQUEST_0_NAME0=Vancouver
L_PAYMENTREQUEST_0_QTY0=1
L_PAYMENTREQUEST_0_AMT0=1799.00
L_PAYMENTREQUEST_0_NAME1=Ottawa
L_PAYMENTREQUEST_0_QTY1=1
L_PAYMENTREQUEST_0_AMT1=1799.00
L_PAYMENTREQUEST_0_NAME2=Calgary
L_PAYMENTREQUEST_0_QTY2=1
L_PAYMENTREQUEST_0_AMT2=1799.00
L_PAYMENTREQUEST_0_NAME3=YoloMD+Verify+Facility
L_PAYMENTREQUEST_0_QTY3=1
L_PAYMENTREQUEST_0_AMT3=599.00
NOSHIPPING=1
PAYMENTREQUEST_0_ITEMAMT=5996.00
PAYMENTREQUEST_0_TAXAMT=0
PAYMENTREQUEST_0_SHIPPINGAMT=0
PAYMENTREQUEST_0_HANDLINGAMT=0
PAYMENTREQUEST_0_SHIPDISCAMT=2398.40
PAYMENTREQUEST_0_INSURANCEAMT=0
PAYMENTREQUEST_0_AMT=3597.60
PAYMENTREQUEST_0_CURRENCYCODE=USD
LOCALECODE=GB
LOGOIMG=My logo
CARTBORDERCOLOR=1761a9
ALLOWNOTE=1
Calling Method -
$paypal->PPHttpPost('SetExpressCheckout', $padata, $PayPalApiUsername, $PayPalApiPassword, $PayPalApiSignature, $PayPalMode);
Response Received
Array
(
[TIMESTAMP] => 2016%2d07%2d13T09%3a22%3a38Z
[CORRELATIONID] => 879b5f075c7c1
[ACK] => Failure
[VERSION] => 109%2e0
[BUILD] => 23255924
[L_ERRORCODE0] => 10413
[L_SHORTMESSAGE0] => Transaction refused because of an invalid argument%2e See additional error messages for details%2e
[L_LONGMESSAGE0] => The totals of the cart item amounts do not match order amounts%2e
[L_SEVERITYCODE0] => Error
)
