Register-ObjectEvent for runspace in an arraylist

I am creating a runspace pool that will have multiple runspaces starting an stopping at different times.

To keep track of this all of my runspaces go into a collection.

I am trying to register an object event for each one so that I can return information from the runspace to the user in the gui.

The part where I am having problems with is here:

$Global:RunspaceCollection
$Global:x = [Hashtable]::Synchronized(@{})

$RunspaceCollection = @()
[Collections.Arraylist]$Results = @()

$RunspacePool = [RunspaceFactory]::CreateRunspacePool(1,5)
$RunspacePool.Open()

$action = {
    Foreach($Runspace in $Global:RunspaceCollection.ToArray()) {
        If ($Runspace.runspace.iscompleted){
            $results.add($runspace.powershell.endinvoke($Runspace.runspace))

            $runspace.powershell.dispose()
            $runspacecollection.remove($Runspace)
            Write-Host "I AM WORKING"
            test-return

    }
}
Function Start-PasswordReset($username) {

    $scriptblock = {
    Param($userame)
    start-sleep -Seconds 10
    $Result = "I have reset" + $username
    $result
}

$Powershell = [PowerShell]::Create().AddScript($ScriptBlock).AddArgument($username)
$Powershell.RunspacePool = $RunspacePool

[Collections.Arraylist]$Global:RunspaceCollection += New-Object -TypeName PSObject -Property @{ 
    Runspace = $PowerShell.BeginInvoke() 
    PowerShell = $PowerShell

}
Register-ObjectEvent -InputObject $runspacecollection[0].Runspace -EventName statechanged -Action $Action
}


}

The code is failing on the register-objectevent line, currently I have hard coded 0 for testing, but that will be the current runspaces number in the final version. I don't know if I have made a small mistake, or have a fundamental lack of understanding of how this works, I'm open to both possibilities!