Exception calling "StartWorkflow" with "3" argument(s): "" - powershell

Question

I am trying to write a powershell script that kicks off two workflows.
One needs to be kicked off only once while the other needs to be run on every item in the list. However I am being plagued by an error and I don't know how to get rid of it. When I add a 4 argument I get the same error. I am running the script as an spshelladmin
Error
Exception calling "StartWorkflow" with "3" argument(s): ""
At C:\cert.ps1:26 char: 29
+ $em = $manager.StartWorkFlow <<<< ($items[0],$emails,$data)
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : DotNetMethodException
Code
$web = Get-SPWeb -Identity "http://portal.com/sites/it"
$manager = $web.Site.WorkFlowManager
$list = $web.Lists["Certificate Tracking"]
$assoc = $list.WorkflowAssociations.GetAssociationByName("Certificate Notification","en-US")
$assoc.AllowAsyncManualStart = $true
$assoc.AllowManual = $true
$emails = $list.WorkflowAssociations.GetAssociationByName("Status Update","en-US")
$emails.AllowAsyncManualStart = $true
$emails.AllowManual = $true
$view = $list.Views["All Items"] #All Items
$items = $list.GetItems($view)
$data = $assoc.AssociationData
$emData = $emails.AssociationData
$count = 0
foreach ($item in $items) {
$wf = $manager.StartWorkFlow($item,$assoc,$data)
}
$em = $manager.StartWorkFlow($items[0],$emails,$emData,$true)
$web.Dispose()

Answer 1

I actually discovered that a specific item I was targeting already had a workflow running on it, I did not place proper checks for the status (check out the comments on this code http://paulryan.com.au/2014/cancel-all-workflows/), very misleading error, I thought I had wrong overload with method call on StartWorkFlow ($item, $association, $data, $true), in SP 2013 there are 4 parameters not sure why the thread title says three... Anyways hope that helps someone.