[HttpException (0x80004005): Failed to Execute URL.]

I am trying to execute my custom Http Handler for pdf request. For the same I have following configuration in my Asp.Net Application :

Application Pool has set as Managed Pipeline mode to Classic mode and Identity to Network Service.

For Handler, I added Script Map in configuration file as :

I ran my application and i am getting this error. Please help to fix this issue.

 Error says: 

 

Failed to Execute URL.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Failed to Execute URL.

Source Error:

 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. 

 

[HttpException (0x80004005): Failed to Execute URL.] System.Web.Hosting.ISAPIWorkerRequestInProcForIIS6.BeginExecuteUrl(String url, String method, String childHeaders, Boolean sendHeaders, Boolean addUserIndo, IntPtr token, String name, String authType, Byte[] entity, AsyncCallback cb, Object state) +919 System.Web.HttpResponse.BeginExecuteUrlForEntireResponse(String pathOverride, NameValueCollection requestHeaders, AsyncCallback cb, Object state) +624 System.Web.DefaultHttpHandler.BeginProcessRequest(HttpContext context, AsyncCallback callback, Object state) +240 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +923 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +137