c# - How to deregister correctly from receiving notifications using IConnectPoint Unadvise? -

in documentation mobile broadband api, says:

the following procedure describes how register notifications.

1.get iconnectionpointcontainer interface calling queryinterface on imbninterfacemanager > object.
2.call findconnectionpoint on returned interface , pass iid_imbnpinevents riid.
3.call advise on returned connection point , pass pointer iunknown interface on > object implements imbnpinevents punk.

notifications can terminated calling unadvise on connection point returned in step 2.

i have got code carries out first 3 steps, , registers mbn events. however, need de-register temporarily receiving these events.
so, after couple of first attempts ended com exceptions, tried following code (with try/catch blocks):

//first notifications  public void registerevent(object iunk, guid guid, out uint storedtag) { iconnectionpoint icp = null; guid curguid = guid; storedtag = 0; if ((curguid == typeof(imbninterfacemanagerevents).guid) )               {   // event, connection point defined on interface manager object   m_interfacemanagercpc.findconnectionpoint(ref curguid, out icp);   // call advise on connection point register   icp.advise(iunk, out storedtag);   //save iconnectionpoint object   interfacemanagercp = icp;  }  //now deregister events  public void deregisterevent(guid guid, uint storedtag) { iconnectionpoint icp = null; guid curguid = guid;  // find appropriate connection point call unadvise on if ((curguid == typeof(imbninterfacemanagerevents).guid) )               {   // call unadvise on saved connection point de-register   interfacemanagercp.unadvise(storedtag); } 

when run code, no errors or exceptions mbn. event handlers aren't de-registered. can still see in log files, mbn events arriving , being handled.

can tell me missing? thank you.

i think figured out problem. have many different types of guids, , thought used same iconnectionpoint, saved same object in registerevent function.

when tried creating new iconnectionpoint object each guid, , saving each iconnectionpoint separately, deregisterevent function worked properly.