yahoo maps api curl settings

Question

How should I configure cURL to retrieve data from the yahoo maps api?

Here is the current code

curl_setopt($ch, CURLOPT_TIMEOUT, 5000);
curl_setopt($ch, CURLOPT_URL, $geocodeurl);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$data = curl_exec($ch);

Which returns a 400 - Bad request HTML file. I've checked $geocodeurl and it is a valid XML file, so I figure the problem must be the cURL options?

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$geocodeurl is

 http://where.yahooapis.com/geocode?appid=** My App ID **&q=Battle%20Creek,MI&gflags=R