Publishing information from Android to PHP Server

So, I'm writing an Android app, and part of it is supposed to use GPS to get longitude / latitude. And these values ​​should be published on the PHP server, in which I also work. The function I post is as follows:

public void doAll() {

Double locLat, locLon;
    try {
    locLat = locManager.getLastKnownLocation(locProvider).getLatitude();
    locLon = locManager.getLastKnownLocation(locProvider).getLongitude();
    } catch (NullPointerException e) {
    locLat = -1.0;
    locLon = -1.0;
    }
try {

    HttpClient client = new DefaultHttpClient();
    //we put all the parameters in the URL itself
    HttpPost request = new HttpPost("http://fatalatour.com/database.php?function=get_all&latitude="+Double.toString(locLat)+"&longitude="+Double.toString(locLon));

    ResponseHandler <String> responseHandler = new BasicResponseHandler();

   //List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
   //nameValuePairs.add(new BasicNameValuePair("latitude", Double.toString(locLat)));
   //nameValuePairs.add(new BasicNameValuePair("longitude", Double.toString(locLon)));
   //request.setEntity(new UrlEncodedFormEntity(nameValuePairs));

   String response = client.execute(request, responseHandler);
   Log.i("HOMI_RESPONSE", response.toString());

}

There is other code with this, but I believe that this is all that actually affects the publication of locLat and locLon.

For the end of the server, I have:

function get_all() {
            $lat = trim($_GET['latitude']);
            $lon = trim($_GET['longitude']);
            // DEBUG
            $f = fopen('debug.log', 'a');
            fprintf($f, 'get_all: '.print_r($_REQUEST, true)."\n");
            $result = mysql_query("SELECT * FROM homi_table");

            $num = 0; //# of homicides

            while ($row = mysql_fetch_assoc($result)) {
                    $d = distance($row['latitude'], $row['longitude'], $lat, $lon, "K");
                    if ($d < 100) { //number to change for distance filter
                            $num += 1;
        echo "fatality:".$row['slug']."~".strtoupper($row['name']).", Age ".$row['age']."\n".$row['date']."\nhttp://projects.latimes.com/homicide/post/".$row['slug']."~".$row['latitude']."~".$row['longitude'];


                            // GH: limiting the number of results to 100
                            if ($num == 100) {
                                    break;
                            }
                    }
            };
            echo $num;
            fprintf($f, "get_all: returning: ".$num."\n");
    }

The problem now is handling $ lat and $ lon. When I hard-code the static number for each of them in PHP, the application works, but when I leave it variable (as it should be), it fails. Any help would be greatly appreciated!