Changing TBitBtn Glyph at runtime

I have a VCL form with a TBitBtn on it and an TImageList containing 2 bitmaps. At runtime i run the following line of code to put one of the bitmaps on my TBitBtn:

ImageList1->GetBitmap(1, BitBtn1->Glyph);

This succesfully puts the bitmap on the TBitBtn. Then later i run the following line of code to change the bitmap and nothing happens:

ImageList1->GetBitmap(0, BitBtn1->Glyph);

Both bitmaps are present in the imagelist (0 and 1). I can swap the lines of code and prove nothing wrong with the imagelist. Here is an old post where a guy seems to solve this in Delphi. I'm thinking i must need to somehow clear the Glyph first but i don't know how in C++.

Here's an example of one way to use it, using a temporary TBitmap to retrieve the image from the TImageList and put it into the glyph at runtime. It does so in this example on the TBitBtn->OnClick event handler.

void __fastcall TForm1::btn1Click(TObject *Sender)
{
    // FOdd is a bool variable defined in the form's private section.
    // It's just being used here as a toggle to flip between the images
    this->FOdd = !this->FOdd;

    TBitmap *bmp = new Graphics::TBitmap();
    try {
        bmp->SetSize(this->ImageList1->Width, this->ImageList1->Height);
        this->ImageList1->GetBitmap(int(FOdd), bmp);
        this->BitBtn1->Glyph->Assign(bmp);
    }
    __finally
    {
        delete bmp;
    }    
}

@relayman357 provided the proper code for the try..__finally block to make this answer more suitable.