adding vdc network to vm in vco 5.1 ( migration issue )

i am not able to add / update vdc org network to vm in vco 5.1

following code was working in vco 4.2.3

task = System.getModule("com.vmware.library.vCloud.vApp.VM").wireVM(
vm,nicNumber,vAppNetworkName,ipAddressingMode,ipAddress,isConnected,macAddress,needsCustomization) ;

but now it is giving exception "network not found".

do i need now to create vApp network first seperate to vdc network?

or is there any other way arround to do it?

thanks in advance for your help