Can't get MAC address for VMware ESXi 5.0

[GoogleCodeExporter]

What steps will reproduce the problem?
class AEsxiServer(object):
    def __init__(self, servername, password,  username='root'):
        self.servername = servername
        self.username = username
        self.password = password
        self.vmlist = []
        self.vmstatusdict = {}
        self.vmmaclist = {}
        self.vmdict = {}
        self.inUseDict = {}

    def connect(self):
        print "connecting to %s" % self.servername
        self.server = VIServer()
        self.server.connect(self.servername, self.username, self.password)
        print "connected to %s" % self.servername
        print "Currently server version is: %s %s" \
            % (self.server.get_server_type(), self.server.get_api_version())

    def get_vmmaclist(self):
        for vmPath in self.get_vmlist():
            vm = self.server.get_vm_by_path(vmPath)
            vminfo = vm.get_properties()
            vmmacinfo = vminfo['mac_address']
            print vmmacinfo

def main():
    print "This is Esxi Server Object"
    S=AEsxiServer('xxxx','xxxx')
    S.connect()
    S.get_vmmaclist()

if __name__ == '__main__':
    main()

results:
print vmmacinfo # it will return "None"

S.get_vmmaclist() will return the following errors
Traceback (most recent call last):
  File "./AsterEsxiServer.py", line 133, in <module>
    main()
  File "./AsterEsxiServer.py", line 125, in main
    asterS.get_vmmaclist()
  File "./AsterEsxiServer.py", line 60, in get_vmmaclist
    vmmacinfo = vminfo['mac_address']
KeyError: 'mac_address'

What is the expected output? What do you see instead?
It should output mac address, but it prompts that don't have the key 
'mac_address'
BTW, I can get 

What version of the product are you using? On what operating system?
RHEL6.5

Please provide any additional information below.

Original issue reported on code.google.com by zhaobin...@gmail.com on 30 Dec 2013 at 6:21