C# - 3CX - Access violation when calling method in PCL through NetNamedPipeBinding -

i trying integrate crm 3cx windows api, have simple windows application lets enter number , button instantiate call, method go , call method in pcl attached 3.

now when pressed button nothing happened, checked syntax many times , looks should , doesn't error out, opened task manager right clicked 3cx while running , pressed debug. once visual studio debugging 3cx clicked call button in windows application , 3cx throws following.

i'm not sure whats going on great, thanks.

call windows applications

private void cmdcall_click(object sender, eventargs e)     {         imakecallservice makecallservice = _makecallchannelfactory.createchannel();         makecallservice.makecall(txtnumber.text.trim());     } 

call method in 3cx pcl

public void makecall(string destination)         {             task.factory.startnew(() =>             {                 _instance._callhandler.makecall(destination, makecalloptions.none);             });         } 

project hierarchy:

this line of code throws access violation

_instance._callhandler.makecall(destination, makecalloptions.none);