cURL post data to asp.net page

[Kabir khan]

I am trying to call the __doPostback javascript function in a asp.net page from php using curl.
I used below code but getting error like
Encountered error while processing the request. Please try again using the Home button.

Diagnostic Information:
Error Type: Exception of type 'System.Web.Htt pUnhandledExcep tion' was thrown.

$url = "http://opanet.hrsa.gov/OPA/Reports/Reports.aspx";
$params = array(
	'aspnetForm' => '',
    '__EVENTTARGET' => 'ctl00$cphMainContent$tvReports',
    '__EVENTARGUMENT' => 'sDaily Reports Menu\\Real-time Reports\\CE Real-time Report'
);


$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 900);
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)");

curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_POST, 1);

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_AUTOREFERER, true );

curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($params));
curl_setopt($ch, CURLOPT_FAILONERROR, 0);

curl_exec($ch);
			
curl_close($ch);