Labtech Error on deleting Network Devices

LTClient-Unable to delete Network Device  192.39.1.100 (1490) using REST. Message: Failed to complete request.  v120.269  3/6/2018 8:18:53 AM:::
LTClient-Unable to delete Network Device  192.39.1.103 (1491) using REST. Message: Failed to complete request.  v120.269  3/6/2018 8:18:54 AM:::
LTClient-Unable to delete Network Device  192.39.1.104 (1494) using REST. Message: Failed to complete request.  v120.269  3/6/2018 8:18:54 AM:::
LTClient-Unable to delete Network Device  192.39.1.108 (1495) using REST. Message: Failed to complete request.  v120.269  3/6/2018 8:18:54 AM:::
LTClient-Unable to delete Network Device  192.39.1.109 (1492) using REST. Message: Failed to complete request.  v120.269  3/6/2018 8:18:54 AM:::
LTClient-Observed unhandled dispatcher exception: LTClient MoveNext Object reference not set to an instance of an object. Object reference not set to an instance of an object.  v120.269  3/6/2018 8:18:54 AM:::
LTClient-Dispatcher Exception: Object reference not set to an instance of an object.
Stacktrace:
   at LTClient.Commands.NetworkDevices.DeleteNetworkDeviceCommandBase.VB$StateMachine_13_DeleteNetworkDevices.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at LTClient.Commands.NetworkDevices.DeleteNetworkDeviceCommandBase.VB$StateMachine_12_Execute.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>b__4(Object state)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
  v120.269  3/6/2018 8:18:54 AM:::
LTClient-Unable to delete Network Device  192.39.1.100 (1490) using REST. Message: Failed to complete request.  v120.269  3/6/2018 8:18:58 AM:::
LTClient-Observed unhandled dispatcher exception: LTClient MoveNext Object reference not set to an instance of an object. Object reference not set to an instance of an object.  v120.269  3/6/2018 8:18:58 AM:::
LTClient-Dispatcher Exception: Object reference not set to an instance of an object.
Stacktrace:
   at LTClient.Commands.NetworkDevices.DeleteNetworkDeviceCommandBase.VB$StateMachine_13_DeleteNetworkDevices.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at LTClient.Commands.NetworkDevices.DeleteNetworkDeviceCommandBase.VB$StateMachine_12_Execute.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>b__4(Object state)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
  v120.269  3/6/2018 8:18:58 AM:::