c# - Lync InvalidStateException when changing contact relationship -

trying change accesslevel of contacts, never succeeds unless use accesslevel.default. here's i've got currently:

private void beginsearchcallback(iasyncresult r) {     object[] asyncstate = (object[])r.asyncstate;     contactmanager cm = (contactmanager)asyncstate[0];     try     {         searchresults results = cm.endsearch(r);         if (results.allresults.count == 0)         {             console.writeline("no results.");         }         else if (results.allresults.count == 1)         {             contactsubscription srs = cm.createsubscription();             contact contact = results.contacts[0];              // change relationship             contact.beginchangesetting(contactsetting.accesslevel, accesslevel.colleague, setprivacycallback, contact);         }         else         {             console.writeline("more 1 result.");         }     }     catch (searchexception se)     {         console.writeline("search failed: " + se.reason.tostring());     }     _client.contactmanager.endsearch(r); } 

a microsoft.lync.model.invalidstateexception blank message gets thrown on line invoking beginchangesetting.

any ideas?

edit:

also, i've checked see if contact setting can modified, , it's true.

var canchange = contact.canchangesetting(contactsetting.accesslevel);