c# - Acces denied error when trying to save a distribution group -

when running code shown below, getting error states:

an unhandled exception of type 'system.unauthorizedaccessexception' occurred in
system.directoryservices.dll. additional information: access denied.

it happens on line : group.save();

i have used username , password in other scripts relating active directory have sufficient access need do. although, haven't tried in relation system.directoryservices.accountmanagement library before.

i using visual studio 2013 running in admin mode, there shouldn't problem command prompt not running in it.

if can give me heads why wouldn't using credentials when saving, appreciated.

try             {                 using (principalcontext pc = new principalcontext(contexttype.domain, "domain", "username", "password"))                 {                                  groupprincipal group = groupprincipal.findbyidentity(pc, "groupname");                     dbaccessmanager dbaccess = new dbaccessmanager();                     sqlconnection connstring = new sqlconnection();                      connstring.connectionstring = system.configuration.configurationmanager.connectionstrings["sqlconnection"].tostring();                     list<employee> sqlemployees = dbaccess.readuserinformation(connstring.connectionstring.tostring());                      foreach (employee emp in sqlemployees)                     {                         userprincipal prinicipaluser = userprincipal.findbyidentity(pc, emp.username);                         userprincipal aduser = userprincipal.findbyidentity(pc, emp.username);                         if (prinicipaluser.ismemberof(group) && string.isnullorempty(emp.saplogin))                         {                             group.members.remove(aduser);                         }                         else if (!prinicipaluser.ismemberof(group) && !string.isnullorempty(emp.saplogin))                         {                             group.members.add(aduser);                         }                     }                     group.save();                                   }             }             catch (directoryservicescomexception e)             {                 console.writeline("exception: " + e.message);             }  

the problem turned out permissions issue on distribution list