Un-removing a button from the toolbar

If a button has been pulled off a toolbar, what function do I call to get it back. I tried these:

pControl->SetHideFlag(XTPControlHideFlags:::xtpNoHide, true);
pControl->SetVisible(true);

neither of them brought back the button.

Thanks

Yes, pulled off by the user in Customize mode.

It's interesting that the button item is still part of the toolbar, but not visible. Why do I need to add it? Can't I flip a switch?

Got it to work.

    CXTPToolBar* pTBar = pCommandBars->GetToolBar(IDR_CUSTOM_TOOLBAR);
    if (pTBar) {
        CXTPControls* pControls = pTBar->GetControls();
         pControls->Add(XTPControlType::xtpControlButton, nID,  ButtonText, nPos);
    }