AIDocument- GetDocument Fails with AIErr DOC?

Question

Hi
I am trying in Illustrator 64 on Windows through a plugin to open  document and get the documents setup.
My code is as follows.
I first acquire the required Suites ( AIDocument, AIDocumentList, AIFilePath etc ) and all the Suites are acquired with NO Errors and have valid pointers
AIErr err = kNoErr;
//Get the page information
  AIDocumentHandle theDocument;ai::UnicodeString uniPath( "C:\\test.ai");
ai::FilePath fpath(uniPath) ;
err = sAIDocumentList->Open( fpath, kAIUnknownColorModel,kDialogOff, false, &theDocument );  
//This conpletes with no errors and the document is opened.  theDocument, aslo has a valid pointer.
AIDocumentSetup docSetup;
err = sAIDocument->GetDocumentSetup(&docSetup);
//This return an error DOC?
I have also tried using AIDocument->GetDocument and AIDocumentList->Activate both after opening the document and they also return DOC?, though the theDocument Handle returned by open document appears to be valid.
Can anyone suggest what I might be doing wrong or a possible way forward?
Thanks
A

Answer 1

Thanks, hooking the kAIDocumentOpenedNotifier worked and my call to GetDocumentSetup works fine, but it still doesnt work where I was calling it before. 
I done think its a document no loaded issue as I am making the call as a result of a button press in the plugin GUI, which triggers a CSXS event, see below.
static void UpdateClickedFunc(const csxs::event::Event* const eventParam, void* const context)
     MyPanelController *myPanelController= (MyPanelController*)context;
     myPanelController->GetDocumentSetupInfo();
From this I get my context and and call my function that reads the document setup for the AIDocumentSuite.
Could it be that in this context, I might not be able to address the AIDocumentSuite. If so how would I get the main context or do I just need to run all my functions in the main body of my plugin.
Amy