Unable to submit form on web page using Invoke-WebRequest

Question

Looking to automate the Web search on HP's website by serial number to get the warranty data.  I am able to successfully get back the web page, and I can populate the fields in the form. However, when I submit the POST, I don't seem to get back any
data.
Please look at the below script and tell me what I'm doing wrong. I am following the FACEBOOK "Example 2" from the Get-Help in PowerShell 3.0.
$Serial = "CND1076GST"
$Url = "http://h20566.www2.hp.com/portal/site/hpsc/public/wc/home/"
$r = Invoke-WebRequest -Uri $Url -SessionVariable HP
If ($r.StatusDescription -eq "OK" ) {
Write-Host $r.StatusDescription
$HP
$form = $r.Forms.Item("wcFormDataItem")
$form.Fields["serialNumber0"] = $Serial
$r2 = Invoke-WebRequest -Uri ($Url + $form.Action) -WebSession $HP -Method POST -Body $form.Fields
$r2.Content | Out-File c:\temp\test.htm -Force
Write-Host $r2.StatusDescription
} Else {
Write-Host $r.StatusDescription
Levi Stevens | Technical Consultant Dell Services

Answer 1

This is how easy it is to lookup the same data from Dell.
$GUID = "cac8daa8-6699-466b-a3d3-f07e571fba1f"
$AppName = "Dell Warranty"
$ServiceTag = "5LCQSY1"
$WebProxy=New-WebServiceProxy -Uri http://xserv.dell.com/services/assetservice.asmx
$WarrantyInformation=$WebProxy.GetAssetInformation($GUID,"Dell Warranty",$ServiceTag)
$WarrantyInformation | Select-Object -ExpandProperty Entitlements
Levi Stevens | Technical Consultant Dell Services