invoke-script permission error

Hi, while i am trying to use the invoke script, getting permission errors.

Error:

====

Invoke-VMScript : 9/23/2011 1:01:39 PM    Invoke-VMScript        Permission to perform this operation was denied.   
At C:\Documents and Settings\gajulg\Local Settings\Temp\f37b4ac0-779c-4c24-a8db-328d1136ec70.ps1:14 char:22
+ $vm | Invoke-VMScript <<<<  -HostCredential $hc -GuestCredential $gc $ifconfig
    + CategoryInfo          : NotSpecified: (:) [Invoke-VMScript], NoPermission
    + FullyQualifiedErrorId : Client20_VmGuestServiceImpl_RunScriptInGuest_ViError,VMware.VimAutomation.ViCore.Cmdlets.Commands.InvokeVmScript

Invoke-VMScript : 9/23/2011 1:01:41 PM    Invoke-VMScript        Permission to perform this operation was denied.   
At C:\Documents and Settings\gajulg\Local Settings\Temp\f37b4ac0-779c-4c24-a8db-328d1136ec70.ps1:15 char:22
+ $vm | Invoke-VMScript <<<<  -HostCredential $hc -GuestCredential $gc $route
    + CategoryInfo          : NotSpecified: (:) [Invoke-VMScript], NoPermission
    + FullyQualifiedErrorId : Client20_VmGuestServiceImpl_RunScriptInGuest_ViError,VMware.VimAutomation.ViCore.Cmdlets.Commands.InvokeVmScript

Scrip:

$hc = Get-Credential
$gc = Get-Credential
foreach ($a in $ips){
$netmask = "255.255.255.0"
$ip1= $a.Ip1
$gw1=$a.gw1
$vmname = $a.Vmname
$vm = Get-VM $vmname
$ifconfig = "ifconfig eth0 $ip1 netmask 255.255.255.0"
$route = "route add default gw $gw1"
Write-Host $vm
$vm | Invoke-VMScript -HostCredential $hc -GuestCredential $gc $ifconfig
$vm | Invoke-VMScript -HostCredential $hc -GuestCredential $gc $route
}