Web Service Error

I have a xml web service and I published it on IIS(localhost). Web service is veriy simple. There is only one method. And there is no exception potential in the web service. I have to use HttpWebRequest instead of adding web reference. I got the following error: "The remote server returned an error: (500) Internal Server Err开发者_运维技巧or". I have checked request xml many times. When I add web referance there is no problem. What's reason of error?

Thanks in advance

Its not possible to tell what the problem is from the information you have provided.

If the web service is one that you have written then you need to get IIS to report a detailed error message on the nature of the problem (by default a restricted error message is shown to prevent would-be attackers obtaining potentially sensitive information), or find another way to obtain detailed error information. Exact instructions on how to do this will depend on the service itself (is this an ASP.Net web service? What version of IIS is this?) however this article - How to Use HTTP Detailed Errors in IIS 7.0 may be of assistance.

If the web service is one that a 3rd party has produced then I'm afraid you need to work with that 3rd party to fix this.

Update: Also try reading Detailed 500 error message, ASP + IIS 7.5 on how to get more detailed error messages.