Convert datetime error

datetime.ps1

$ get-date -OutVariable sd "6/2/2017 03:58"

06 February 2017 03:58:00

$ $sd | gm


   TypeName: System.DateTime

Name                 MemberType     Definition
----                 ----------     ----------
Add                  Method         datetime Add(timespan value)
....

$ Get-MessageTrackingLog -Start $sd
Cannot process argument transformation on parameter 'Start'. Cannot convert the "System.Collections.ArrayList" value of type "System.Collections.ArrayList" to type "System.DateTime".
    + CategoryInfo          : InvalidData: (:) [Get-MessageTrackingLog], ParameterBindin...mationException
    + FullyQualifiedErrorId : ParameterArgumentTransformationError,Get-MessageTrackingLog