LDAP Authentication Question

[verdrm]

I am having trouble authenticating users with LDAP. I can authenticate users when I use "CN" or "givenName" but not when I use "samaccountname", which is the username. CN is just the first + last name.

 

Does anyone know why only CN and not samaccountname works?

 

$strUsername = "test"; 
$strPassword = "pass";

		$dn = 'samaccountname=' . $strUsername . ',OU=Staff,DC=mydomain,DC=com';

		$strDomain = "ldap://localhost/";

		$bolAuth = false;

		// connect to ldap server
		$port = "389";
		$objConn = ldap_connect($strDomain);

		if ($objConn)
		{
			if ( $strPassword != null )
			{
				$bolAuth = ldap_bind($objConn, $dn, $strPassword);
				if ( $bolAuth ) {

					$search_id = ldap_search($objConn, "OU=Staff,DC=mydomain,DC=com", "(samaccountname=".$strUsername.")");
					$entries = ldap_get_entries($objConn, $search_id);
					if ($entries["count"] == 1) {
						$first_name = $entries[0]["givenname"][0];;
						$last_name = $entries[0]["cn"][0]; 

					}
				}	 

			}


			ldap_close($objConn);
		}	

		if($bolAuth==false){
			echo "fail";
			return false;
		}