[libvirt-users] Problem attaching device

I keep getting an error when I try to attach a device in the libvirt api through python The python code is: conn=libvirt.open('qemu:///system') dom = conn.lookupByName("fedoratest") if dom.info()[0]==1: dom.attachDevice('net.xml') And I keep getting: "libvirtError: XML description not well formed or invalid The xml is a simple network card that works fine in virsh. It is just: #cat net.xml <interface type='network'> <mac address='52:54:00:00:fe:5c'/> <source network-'default'/> target dev='vnet1'/> </interface> I've tired giving it the full path still no luck. Thanks in advance,