Open Bing map layer using vb.net

i try to open bing map from vb.net but i could not
i try the url link in bing it works good but when i put the code in the vb.net
it did not work in mapwingis
i search everywhere but i found no answer or example of solve of this problem
please if anyone know how to solve this problem

    Dim BingMapsKey As String = "j9zDXCzbxVa..........."

    Dim url As String = "http://dev.virtualearth.net/REST/v1/Imagery/Map/AerialWithLabels/30.251085,31.481398/14?mapSize=1000,1000&key=" & BingMapsKey
    mainmap.AddLayer(url, True)