Import-PSSnapin cmdlet to compensate for the shortcomings of the built-in snap-in cmdlets.

Import-PSSnapin.ps1

function Import-PSSnapin {
<#
.Synopsis
    Adds a Windows PowerShell snap-in with the specified name to the current session.
    This cmdlet will not throw an exception if the specified snap-in is already present in the session.
.Description
    Helper function to safely add a Windows PowerShell snap-in with the specified name to the current session.
.Parameter Name
    The name of the snap-in to import.
#>
[CmdletBinding()]
param(
    [Parameter(Position=1)]
    [string]$Name
)
    $snapinIsNotInSession = -Not (Get-PSSnapin $Name -ErrorAction SilentlyContinue)

    if ($snapinIsNotInSession) {
        Add-PSSnapin $Name
    }
}