Error 17500 The instance of the .NET class could not be retrieved. Object reference not set to instance of an object

[hallawt2004]

I'm getting this message when I try to use a DotNet adapter in TestStand.  

The instance of the .NET class could not be retrieved.
Object reference not set to an instance of an object.
Source:  VTF   at CPS.Engines.SelectCom.Stack.TransportLayerComms..ctor(GenericComms _physicalLayer, EngineLogDelegate _log)
   at CPS.Engines.SelectCom.SelectComMasterEngine..ctor(GenericComms _comms, List`1 _supportedProtocols, EngineLogDelegate _log)
   at CPS.Engines.SelectCom.SelectComMasterEngine..ctor(GenericComms _comms, ProtocolStack _protocol, EngineLogDelegate _log)

Error code:  -17500; Operation Failed.

I have succefully ran this application in LabVIEW, using DotNet objects.  I have attached both the Sequence file (which errors out, and the Labview application, which works.

Hoping for any help I can get.

[dug9000]

I'm assuming the step you are getting the error on is the one that constructs the SelectComMasterEngine (i.e. ContructSelectComMasterEngine). Is this correct?

I see two potential problems with that step:

1) The argument you are passing for the first parameter is not the one you set in the first step. You are passing FileGlobals.CommsSetting rather than Locals.CommsSetting. FileGlobals.CommsSetting is likelly a null reference.

2) You are passing in a variable for the _log parameter that is also potentially unset. At least I don't see anywhere where it is getting set before it's being used.

Hope this helps,

-Doug