LDAP active directory search in c#

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C#3.0

C#

ASP.NET

i m getting this.. when i run my code. suggest me i good reason for this ....

at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail)
at System.DirectoryServices.DirectoryEntry.Bind()
at System.DirectoryServices.DirectoryEntry.get_AdsObject()
at System.DirectoryServices.PropertyValueCollection.PopulateList()
at System.DirectoryServices.PropertyValueCollection..ctor(DirectoryEntry entry, String propertyName)
at System.DirectoryServices.PropertyCollection.get_Item(String propertyName)
at System.DirectoryServices.DirectorySearcher.get_SearchRoot()
at System.DirectoryServices.DirectorySearcher.FindAll(Boolean findMoreThanOne)
at System.DirectoryServices.DirectorySearcher.FindOne()
at FormsAuthAD.LdapAuthentication.GetGroups() in D:\Amit\New folder\New folder (3)\New folder (3)\New folder\FormsAuthAD\FormsAuthAD\LdapAuthentication.cs:line 80



my code are as:




public bool IsAuthenticated(string domain, string username, string pwd)
{
string domainAndUsername = domain + @"\" + username;
DirectoryEntry entry = new DirectoryEntry(_path, domainAndUsername, pwd);

try
{
//Bind to the native AdsObject to force authentication.
object obj = entry.NativeObject;

DirectorySearcher search = new DirectorySearcher(entry);

search.Filter = "(SAMAccountName=" + username + ")";

search.PropertiesToLoad.Add("cn");

SearchResult result = search.FindOne();

if (null == result)
{
return false;
}

//Update the new path to the user in the directory.
_path = result.Path;
_filterAttribute = (string)result.Properties["cn"][0];
}
catch (Exception ex)
{
throw new Exception("Error authenticating user. " + ex.Message);
}

return true;
}

public string GetGroups()
{
//DirectoryEntries searchRoot = new DirectoryEntries(_path);
DirectorySearcher search = new DirectorySearcher(_path);

search.Filter = "(cn=" + _filterAttribute + ")";

search.PropertiesToLoad.Add("memberOf");
StringBuilder groupNames = new StringBuilder();

try
{


SearchResult result = search.FindOne();
int propertyCount = result.Properties["memberOf"].Count;
string dn;
int equalsIndex, commaIndex;

for(int propertyCounter = 0; propertyCounter < propertyCount; propertyCounter++)
{
dn = (string)result.Properties["memberOf"][propertyCounter];
equalsIndex = dn.IndexOf("=",1);
commaIndex = dn.IndexOf(",", 1);
if(-1 == equalsIndex)
{
return null;
}
groupNames.Append(dn.Substring((equalsIndex + 1), (commaIndex - equalsIndex) - 1));
groupNames.Append("|");
}
}
catch(Exception ex)
{
throw new Exception("Error obtaining group names. " + ex.Message);
}
return groupNames.ToString();
}
}