Error when values = 0

Question

Alright well my script currently is working great but there
is a slight problem.
My TileList right now displays coordinates / images and
whenever the coordinate has a value of 0 in either x or y it gives
an error maybe because it believe there is no integer or there is
no value i'm not sure as to why this is the error i get.
TypeError: Error #1009: Cannot access a property or method of
a null object reference.
at environment/::resultHandler()
at environment/__sendCoord_result()
at
flash.events::EventDispatcher/flash.events:EventDispatcher::dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.rpc.http.mxml::HTTPService/
http://www.adobe.com/2006/flex/mx/internal::dispatchRpcEvent()
at mx.rpc::AbstractInvoker/
http://www.adobe.com/2006/flex/mx/internal::resultHandler()
at mx.rpc::Responder/result()
at mx.rpc::AsyncRequest/acknowledge()
at ::DirectHTTPMessageResponder/completeHandler()
at
flash.events::EventDispatcher/flash.events:EventDispatcher::dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at flash.net::URLLoader/flash.net:URLLoader::onComplete()
Help is very much appreciated.

Answer 1

well when I run the debug it says
that the tileData = event.result.tiles.tile part is the error
and it also comes from my httpservice
Code:
private function resultHandler(event:ResultEvent):void {
tileData = event.result.tiles.tile;
<mx:HTTPService id="sendCoord" url="
http://www.chimeraonlinerpg.com/CO/XML/environment.php"
result="resultHandler(event)" useProxy="false" method="POST">
<mx:request xmlns="">
<xCoord>{curXCoord}</xCoord>
<yCoord>{curYCoord}</yCoord>
</mx:request>
</mx:HTTPService>