While updating an existing LACP config on a dvswitch , eg increasing number of lacp uplinks; pyvmomi returns ''A general system error occurred: Not initialized''

I have an existing LACP config on Dvswitch using 2 esxi hosts. In the original config I had the 2 lacp uplinks.Later, I create the following lacp group spec:
(vim.dvs.VmwareDistributedVirtualSwitch.LacpGroupSpec) {
dynamicType = ,
dynamicProperty = (vmodl.DynamicProperty) [],
lacpGroupConfig = (vim.dvs.VmwareDistributedVirtualSwitch.LacpGroupConfig) {
dynamicType = ,
dynamicProperty = (vmodl.DynamicProperty) [],
key = '517417729',
name = ,
mode = ,
uplinkNum = 3,
loadbalanceAlgorithm = ,
vlan = ,
ipfix = ,
uplinkName = (str) [],
uplinkPortKey = (str) []
},
operation = 'edit'

I use the following api call to commit my changes :
vim.dvs.VmwareDistributedVirtualSwitch.UpdateLacpGroupConfig(lacp_group_config)

I get the message:
vim.TaskInfo) {
dynamicType = ,
dynamicProperty = (vmodl.DynamicProperty) [],
key = 'task-14006',
task = 'vim.Task:task-14006',
description = ,
name = vim.dvs.VmwareDistributedVirtualSwitch.UpdateLacpGroupConfig,
descriptionId = 'dvs.VmwareDistributedVirtualSwitch.updateLacpGroupConfig',
entity = 'vim.dvs.VmwareDistributedVirtualSwitch:dvs-1906',
entityName = 'Test_DVS01',
locked = (vim.ManagedEntity) [],
state = 'error',
cancelled = false,
cancelable = false,
error = (vmodl.fault.SystemError) {
dynamicType = ,
dynamicProperty = (vmodl.DynamicProperty) [],
msg = 'A general system error occurred: Not initialized',
faultCause = ,
faultMessage = (vmodl.LocalizableMessage) [],
reason = 'Not initialized'
},
result = ,
progress = ,
reason = (vim.TaskReasonUser) {
dynamicType = ,
dynamicProperty = (vmodl.DynamicProperty) [],
userName = 'VSPHERE.LOCAL\Administrator'
},
queueTime = 2013-11-21T21:52:18.808619Z,
startTime = 2013-11-21T21:52:18.815232Z,
completeTime = 2013-11-21T21:52:18.851323Z,
eventChainId = 171216,
changeTag = ,
parentTaskKey = ,
rootTaskKey = ,
activationId =

Start at vim.dvs.VmwareDistributedVirtualSwitch.UpdateLacpGroupConfig and review the Lと思acpGroupSpec shown in the report, especially the edit operation and uplinkNum change. Reproduce the update against an existing DVS configuration and compare the resulting task state; done means increasing the LACP uplink count no longer returns the reported 'Not initialized' system error.