[closed] Map doesn’t get “shown” on the Qt widget with Leaflet API

See the snapshot below. I am able to click markers on this map and I can also display the lat longs on it.

But I just can't see the map!

The code is here. This function gets called first.

function displayMapAndClick ()
{
    map = L.map ('map', 
    {
        dragging: true,
    }).setView([51.505, -0.09], 13, true);

    L.tileLayer('http://{s}.tile.cloudmade.com/API-key/997/256/{z}/{x}/{y}.png', 
    {
        attribution: 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Imagery © <a href="http://cloudmade.com">CloudMade</a>',
        maxZoom: 13,
        styleId: 997
    }).addTo(map);

    selectCenterPoint ();
}

The Qt's code which accesses the open street map url is:

void Map::geoCode (QString local)
{
    clearCoordinates ();

    QString url = "http://openstreetmap.org/";
    manager->get (QNetworkRequest (QUrl (url)));
    ++pendingRequests;
}