Powershell v3 Invoke-WebRequest HTTPS error

Using Powershell v3's Invoke-WebRequest and Invoke-RestMethod I have succesfully used the POST method to post a json file to a https website.

The command I'm using is

 $cert=New-Object System.Security.Cryptography.X509Certificates.X509Certificate2("cert.crt") Invoke-WebRequest -Uri https://IPADDRESS/resource -Credential $cred -certificate $cert -Body $json -ContentType application/json -Method POST

However when I attempt to use the GET method like:

 Invoke-WebRequest -Uri https://IPADDRESS/resource -Credential $cred -certificate $cert -Method GET

The following error is returned

 Invoke-RestMethod : The underlying connection was closed: An unexpected error occurred on a send. At line:8 char:11+ $output = Invoke-RestMethod -Uri https://IPADDRESS/resource -Credential $cred+           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest)      [Invoke-RestMethod], WebException+ FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

I have attempted using the following code to ignore SSL cert, but I'm not sure if its actually doing anything.

 [System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}

What might be going wrong here and how to fix it?