Plugin ToolBarBottun Not Appearing

This code runs without throwing exceptions, but the button does not appear in Acrobat DC Pro.

However, if I go into the Customize Quick Tools menu, I can get it to appear by adding it from the File category.

// Create our Toolbar Button
AVIcon icon = (AVCursor)LoadBitmap(gHINSTANCE, MAKEINTRESOURCE(IDB_RAPIDBITMAP));
AVToolButton MyButton = AVToolButtonNew(ASAtomFromString("SPRP:RapidButton"), icon, FALSE, FALSE);
AVToolButtonSetHelpText(MyButton, "Rapid Bookmarks");
AVToolButtonSetExternal(MyButton, TOOLBUTTON_EXTERNAL | TOOLBUTTON_INTERNAL);

AVToolButtonSetExecuteProc(MyButton, ASCallbackCreateProto(AVExecuteProc, MyPluginCommand), NULL);
AVToolButtonSetComputeEnabledProc(MyButton,
  ASCallbackCreateProto(AVComputeEnabledProc, MyPluginIsEnabled), (void *)pdPermEdit);

// Retrieve the File Tool Bar
const char * toolbarName = "File";
AVToolBar ToolBar = AVAppGetToolBarByName(toolbarName);

// Attach the Button
AVToolBarAddButton(ToolBar, MyButton, FALSE, NULL);
AVToolBarUpdateButtonStates(NULL);

return true;