Why is a known PHP file giving a 404?

Bit of an odd one this, I’ve got a PHP file which sometimes gives a 404 error. It’s an ajax callback page for a wordpress plugin I’ve made.

For example:

This works : http://ledhdtvtelevisions.com/wp-content/plugins/amazon-affiliate-link-localizer/ajax.php?strTld=co.uk&strAffiliateId=pcrev05&strLinks=B001JKTC9A|B0015TG12Q

But this doesn’t: http://ledhdtvtelevisions.com/wp-content/plugins/amazon-affiliate-link-localizer/ajax.php?strAction=search&strLink=http://www.amazon.com/dp/B000IZGIA8

Obviously the PHP file is there or the first link wouldn’t work, so why doesn’t the second link work?

What’s interesting is that the troublesome link work fine on my server using the exact same code: http://petewilliams.info/blog2/wp-content/plugins/amazon-affiliate-link-localizer/ajax.php?strAction=search&strLink=http://www.amazon.com/dp/B000IZGIA8

Sadly I don’t have direct access to the server that is having the problem, but I can ask for changes to be made. It’s not just this site that is having the problem, some other users of the script are having the same issue.

Here’s that file’s source code, there’s not much to it:

<?php

header("Content-type: application/javascript");

switch ( $_REQUEST['strAction'] ) {
    case 'search':
        searchLink();
        break;
    case 'version':
        echo "1.7b";
        break;
    default:
        checkLinks();
        break;
}

function checkLinks() {

    // get URL
    $strTld         = $_REQUEST['strTld'];
    $strAffiliateId = $_REQUEST['strAffiliateId'];
    $strLinks       = $_REQUEST['strLinks'];
    $arrLinks       = explode( '|', $strLinks );

    foreach ( $arrLinks as $strAsin ) {

        $strLink = "http://www.amazon.$strTld/exec/obidos/ASIN/$strAsin/$strAffiliateId";

        $arrHeaders = get_headers($strLink, 1);

        // if not found, then search for it
        if ( strpos( $arrHeaders[0], '404' ) || strpos( $arrHeaders[1], '404' ) ) {
            echo "arrLinksToCheck[ '$strAsin' ].searchLink();n";
        } else {
            echo "arrLinksToCheck[ '$strAsin' ].localiseLink();n";
        }

    }
}

function searchLink() {
        $strHtml = file_get_contents( $_REQUEST['strLink'], false, null, -1, 100000 );

        $strPattern = '/canonical" href="http://(.*)/(.*)/dp/([A-Z0-9]{10})/';

        preg_match( $strPattern, $strHtml, $arrMatches );
        $strTitle = str_replace(  '-', '%20', $arrMatches[2] );

        // the canonical ASIN is sometimes different to the original one which confuses the JS, so use the one in the original link
        $strPattern2 = '//([A-Z0-9]{10})/';
        preg_match( $strPattern2 , $_REQUEST['strLink'], $arrUrlMatches );

        $strAsin = is_array( $arrUrlMatches ) ? $arrUrlMatches[1] : $arrMatches[3];

        echo "arrLinksToCheck[ '{$strAsin}' ].writeSearchLink( '$strTitle' );n";

}

Anyone got any ideas as to what’s up?

Thanks

Pete