Need Help in SSIS Script Task

Hi All

I have created the reports using SSRS. Through application, i have deployed the reports in the IISServer.
I have created a project in SSIS, where i have added the script task control which will read the reports path and export the report to PDF format and save into the configured location.

For example,
IIS virtual directory name is Snapshot, where the reports reside. I'm trying to access the location like http://localhost/snapshot/?<Reportname> &rs:Command=Render&rs:Format=PDF

I am using vb.net code inside the script task to access the url and export the report to pdf. Here i am using webrequest class to access the url like webrequest.create(url) and setting the credentials as default credentials.
Then checking the webrequest.getresponse(). If i get the response, then i would read the value as bytes and write into the configured location.

I am not getting the response, it throws the exception like below
"System.Net.WebException: The remote server returned an error: (500) Internal Server Error.at System.Net.HttpWebRequest.GetResponse()"

Thanks in Advance