Saving generated book components with ExtendScript doesn't work

I am working on a script to use existing non-generated book files to create a new FrameMaker book. I have the following code to create a TOC and list of figures:

    var loc = newPath.substring(0, newPath.lastIndexOf("\\"));
    bookToc = oBk.NewSeriesBookComponent (oBk.FirstComponentInBook);
    bookToc.BookComponentType = Constants.FV_BK_TOC;
    bookToc.Name = loc + "\\TOC.fm";
    bookToc.ExtractTags = vExtractList;
    bookToc.GenerateInclude = 1;

// add LOF to oBk and set it up (type = Constants.FV_BK_LIST_FIGURE)
    bookLof = oBk.NewSeriesBookComponent (bookToc); 
    bookLof.BookComponentType = Constants.FV_BK_LIST_FIGURE;
    bookLof.Name = loc + "\\LOF.fm";
    bookLof.ExtractTags = new Strings ("Figure1", "Figure");
    bookLof.GenerateInclude = 1;
    $.writeln("bookLof.ObjectValid() = ",  bookLof.ObjectValid());
    
// generate TOC and LOF
    oBk.SimpleGenerate(0,1);
    
// save and close TOC and LOF - THIS ALWAYS FAILS
// but if I comment out the next four lines the script runs to completion
saveObject(bookToc,bookToc.Name);
bookToc.Close(1);
saveObject(bookLof,bookLof.Name);
bookLof.Close(1);

// update oBk
    $.writeln(bookToc.ObjectValid());
   bkUpdate(oBk);

// save and close new book..."saveObject" works fine for books and non-generated files
saveObject(oBk,oBk.Name);
oBk.Close(1);

 I cannot save and close the TOC and LOF files. If I comment out those lines the script runs to completion. The generated files are added to the book and appear in separate windows. At this point I can manually save and close the generated files, but I'd like the script to handle that.

Here's the "saveObject" and "bkUpdate" code...the ESTK is telling me that "obj.Save is not a function":

function saveObject(obj,saveAsName)
{
    saveParams = GetSaveDefaultParams();
    returnParams = new PropVals();  
    obj.Save(saveAsName, saveParams, returnParams);
    return 0;
}    

function bkUpdate(obj)
{
    var updateParams = GetUpdateBookDefaultParams();
    var updateReturnParams = new PropVals();  
    var index = GetPropIndex(updateParams, Constants.FS_UpdateBookGeneratedFiles);
    updateParams[index].propVal.ival = true;
    var index = GetPropIndex(updateParams, Constants.FS_MakeVisible);
    updateParams[index].propVal.ival = true; 
    obj.UpdateBook(updateParams, updateReturnParams);
    return 0;
}    

 As always, any advice is most appreciated.