Strange API issue when looping in PHP - php

Question

I'm working with this API here: https://gatewaydtx1.giact.com/gVerifyV2/POST/Verify.asmx?op=Call using curl in php. I am able to do a test just fine on a single call to the API. However when I try to loop over several records, I get an error on every attempt after the first one.
Here's my code:
<?
//set the variables for posting
$CompanyID = "123";
$Token = "013443234-224e-4f46-bad4-6693deae2231";
$CheckNumber = "1";
$Amount = "30";
$UniqueID = "111";
$url = "https://gatewaydtx1.giact.com/gVerifyV2/POST/Verify.asmx/Call";
//Get the records from table
$sql = "SELECT id,account_no,routing_no FROM banktable WHERE(status = 'queued') LIMIT 0,100";
$result = mysql_query($sql) or die("Error: " . mysql_error() . "<br>");
while($row = mysql_fetch_array($result)) {
$RoutingNumber = $row['routing_no'];
$AccountNumber = $row['account_no'];
//Do the curl
$ch = curl_init();
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_VERBOSE, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible;)");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_URL, $url );
$post_array = array(
"CompanyID"=>$CompanyID,
"Token"=>$Token,
"RoutingNumber"=>$RoutingNumber,
"AccountNumber"=>$AccountNumber,
"CheckNumber"=>$CheckNumber,
"Amount"=>$Amount,
"UniqueID"=>$UniqueID,
);
//url-ify the data
foreach($post_array as $key=>$value){
$post_array_string .= $key.'='.$value.'&';
}
$post_array_string = rtrim($post_array_string,'&');
//set the url, number of POST vars, POST data
curl_setopt($ch,CURLOPT_POST,count($post_array ));
curl_setopt($ch,CURLOPT_POSTFIELDS,$post_array_string);
$response = curl_exec($ch);
echo $response;
curl_close($ch);
}
?>
And here's what this code outputs after looping 4 rows:
<?xml version="1.0" encoding="utf-8"?>
<string xmlns="http://www.giact.com/webservices/gVerifyV2/">33302261|true|No Data|ND00</string>
Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).
Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).
Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).
Note that the first record it tried produced a correct result. After that, the errors. And even though I mention my loop specifically here, I should note that this also happens if I simply hard code two or more curls on the page.

Answer 1

//url-ify the data
foreach($post_array as $key=>$value){
$post_array_string .= $key.'='.$value.'&';
}
$post_array_string = rtrim($post_array_string,'&');
I think you need to clear the $post_array_string variable in each loop.
unset($post_array_string);

Answer 2

Before:
foreach($post_array as $key=>$value){
Add:
$post_array_string = '';
Or you can use http_build_query() function.