在现有的v-net恐惧中创建Azure负载均衡器“不是负载均衡器引用的所有后端IP配置”

我尝试通过powershell在azure上创建一个负载均衡器，但是如果我使用来自不同资源组的现有vnet，我会收到错误 . （并非Load Balancer引用的所有后端IP配置） . 以后应将负载均衡器用于VM Scale Set .

但我没有为BackendAddressPoolConfig设置v-net和IP，我也看不到如何做到这一点 .

$vnet= Get-AzureRmVirtualNetwork -Name $vnetname -ResourceGroupName $vnetrg -ErrorAction Stop
$subnetMain = $vnet.Subnets[2]
$subNetName = $subnetMain.Name
$frontendIP = New-AzureRmLoadBalancerFrontendIpConfig -Name LB-Frontend `
                                               -SubnetId $subnetMain.Id
$beaddresspool= New-AzureRmLoadBalancerBackendAddressPoolConfig -Name "LB-backend" 
$inboundNATRule1= New-AzureRmLoadBalancerInboundNatRuleConfig -Name "RDP" `
                                           -FrontendIpConfiguration $frontendIP `
                                           -Protocol TCP `
                                           -FrontendPort 3389 `
                                           -BackendPort 3389
$healthProbe = New-AzureRmLoadBalancerProbeConfig -Name "HealthProbe" `
                                           -RequestPath "Default.htm" `
                                           -Protocol http -Port 80 `
                                           -IntervalInSeconds 15 `
                                           -ProbeCount 2
$lbrule = New-AzureRmLoadBalancerRuleConfig -Name "HTTP" `
                                           -FrontendIpConfiguration $frontendIP `
                                           -BackendAddressPool $beAddressPool `
                                           -Probe $healthProbe `
                                           -Protocol Tcp `
                                           -FrontendPort 80 `
                                           -BackendPort 80

$nrplb = New-AzureRmLoadBalancer -ResourceGroupName $currentrg `
                                           -Name "NRP-LB" `
                                           -Location $loc `
                                           -FrontendIpConfiguration $frontendIP `
                                           -InboundNatRule $inboundNATRule1 `
                                           -LoadBalancingRule $lbrule `
                                           -BackendAddressPool $beAddressPool `
                                           -Probe $healthProbe

我必须为后端设置IP配置吗？但是怎么样？或者是出了什么问题？