Connectivity lost after changing the ip

Hi I have this situation:

I have a template with one Vm. I  clone a app and change the app by adding the same VM to  the app.

Now I have an app with 2 identical VM (same IP) and because of this I cant start the 2 machines at the same time. 

So I use this to update the Ip of one of the machine (I have just 1 NIC and before doing this at power one the first VM connect to internet):

List<VirtualNetworkCard> nics1 = VM.GetNetworkCards(vcloudexec.GetClient(), myVM.Reference);

nics1[0].UpdateIpAddress(ippp);

myVM.UpdateNetworkCards(nics1).WaitForTask(0);

Where "ippp" is new ip which is the last increased by 1.

Now I cat start the two WM but at the one with ip changed I cant connect to internet. The connection icons show the sign of limited network connection.

Strange is if I do this Ip change manually everything is OK.

Is require other code to update the app after changing the IP? I have tried to remove and add the NIC with the same effect. When done programmatically no internet connection when done manually everything is OK.