SharePoint 2010 - the request failed with http status 401 unauthorized

I was getting below error, when I am trying to connect to SharePoint 2010 SiteData.asmx webservice. from VS 2010 asp.net website
the request failed with http status 401 unauthorized

Solution
System.Net.NetworkCredential myCredential = new System.Net.NetworkCredential();

myCredential.UserName = "";
myCredential.Password = "";
 
The above code has been changed as
myCredential = new NetworkCredential("username", "password", "domain");
 
Started working