How to update recurring profile for paypal express checkout recurring payments

Question

On my website I am using paypal express checkout and creating recurring profiles.

I want to update the amount for a recurring profile and is calling the updaterecurring function as:

if($Post['update'] == 1) 
{
  $nvpstr="&PROFILEID=".$profileID;
  $nvpstr.="&AMT=1.2";
  $nvpstr.="&PROFILESTARTDATE=".urlencode("2014-03-01T0:0:0");
  $resArray=hash_call("UpdateRecurringPaymentsProfile",$nvpstr);
  $ack = strtoupper($resArray["ACK"]);
  return $resArray;
} 
else
{
  $resArray = CallShortcutExpressCheckout ($paymentAmount, $currencyCodeType, $paymentType, $returnURL, $cancelURL);
  $ack = strtoupper($resArray["ACK"]);
  if($ack=="SUCCESS" || $ack=="SUCCESSWITHWARNING")
  {
  // if SetExpressCheckout is returned with success, move to paypal site for payments.
  RedirectToPayPal ( $resArray["TOKEN"] );
  } 

}

The update recurring profile is giving me error on paypal sandbox page. Do I need to call SetExpressCheckout before the updaterecurring call?

I am using the paypal integration lib from https://github.com/hrendoh/PayPal-Recurring-Payment-example