title: Paypal Error Message 'Buyer cannot pay.' when trying to capture multiple times
body: <p>I use Express Checkout of Paypal. The problem is, when I try to capture authorization multiple times. I got fail response.</p>
  
  <p>Total amount of this payment is 800.</p>
  
  <p>I want to capture authorization of each item.</p>
  
  <p>this is the first request. I try to capture item amount in 'L_AMT0'</p>
  
  <pre><code>    $captureData = array(
          'AUTHORIZATIONID'   =&gt; $payment-&gt;payment_id,
          'AMT'               =&gt; $amount,  // '41.00'
          'COMPLETETYPE'      =&gt; 'Complete',
          'CURRENCYCODE'      =&gt; 'SGD',
      );
  
      $response = $merchant-&gt;doCapture($captureData);
  </code></pre>
  
  <p>This is some parts of the first response after capture the first item.
  Everything looks fine.</p>
  
  <pre><code>'ACK' =&gt; string 'Success' (length=7)
  'TRANSACTIONTYPE' =&gt; string 'cart' (length=4)
  'PAYMENTTYPE' =&gt; string 'instant' (length=7)
  'AMT' =&gt; string '800.00' (length=6)
  'L_AMT0' =&gt; string '759.00' (length=6)
  'L_AMT1' =&gt; string '41.00' (length=5)
  </code></pre>
  
  <p>So I make a second amount and got this error.</p>
  
  <pre><code>'AUTHORIZATIONID' =&gt; string '*****************' (length=17)
  'TIMESTAMP' =&gt; string '2015-09-09T09:14:51Z' (length=20)
  'CORRELATIONID' =&gt; string '*************' (length=13)
  'ACK' =&gt; string 'Failure' (length=7)
  'VERSION' =&gt; string '115' (length=3)
  'BUILD' =&gt; string '17972692' (length=8)
  'L_ERRORCODE0' =&gt; string '10606' (length=5)
  'L_SHORTMESSAGE0' =&gt; string 'Buyer cannot pay.' (length=17)
  'L_LONGMESSAGE0' =&gt; string 'Transaction rejected, please contact the buyer.' (length=47)
  'L_SEVERITYCODE0' =&gt; string 'Error' (length=5)
  </code></pre>
  
  <p>So can you help me find what is wrong with my request?</p>