Parsing XML in VB with XPath

I am trying to read through a directory of xml files and read values from them if they exist. Here is an example XML file:

<?xml version="1.0" encoding="utf-16"?>
<SegmentRequirement xmlns:xsd="http://ift.tt/tphNwY" xmlns:xsi="http://ift.tt/ra1lAU" xmlns="Manufacturing.MESProcessApp.S95Entities">
<ID>97_Transmission Fluid Fill</ID>
<Segment>
    <ID>Transmission Fluid Fill</ID>
</Segment>
<ProductionParameters> 
    <ProductionParameter>
      <Name>Transmission_FillMaxVolumeWarning</Name>
      <Description>Screen Warning if above this level</Description>
      <Value>15.0</Value>
      <ValueUnitOfMeasure>qt.</ValueUnitOfMeasure>
    </ProductionParameter>
    <ProductionParameter>
      <Name>Transmission_FillMinVolumeWarning</Name>
      <Description>Screen Warning if below this level</Description>
      <Value>11.0</Value>
      <ValueUnitOfMeasure>qt.</ValueUnitOfMeasure>
    </ProductionParameter>
    <ProductionParameter>
      <Name>Transmission_FillSpecName</Name>
      <Description>Name for users to identify specification</Description>
      <Value>Eaton-Fuller Standar</Value>
      <ValueUnitOfMeasure></ValueUnitOfMeasure>
    </ProductionParameter>
  </ProductionParameters>
  </SegmentRequirement>

And here is the code I'm trying to use.

Module Module1

Sub Main()

    Dim Transmission_FillSpecName As XmlNode
    Dim m_xmld As XmlDocument

    Dim di As New DirectoryInfo("C:\MESChassisXmlFiles\MESChassisXmlFiles\Transmission Fluid Fill\")
    ' Get a reference to each file in that directory.
    Dim fiArr As FileInfo() = di.GetFiles()
    ' Display the names of the files.
    Dim fri As FileInfo
    For Each fri In fiArr
        m_xmld = New XmlDocument()
        Dim nsmgr As XmlNamespaceManager = New XmlNamespaceManager(m_xmld.NameTable)
        nsmgr.AddNamespace(String.Empty, "Manufacturing.MESProcessApp.S95Entities")
        nsmgr.AddNamespace("xsi", "http://ift.tt/ra1lAU")
        nsmgr.AddNamespace("xsd", "http://ift.tt/tphNwY")
        m_xmld.Load(fri.FullName.ToString)
        Console.WriteLine("Loaded: " + fri.Name.ToString)
        Dim root As XmlElement = m_xmld.DocumentElement
        Try
            Transmission_FillSpecName = root.SelectSingleNode("/SegmentRequirement/ProductionParameters/ProductionParameter[Name='Transmission_FillSpecName']/Value", nsmgr)
            Console.WriteLine(Transmission_FillSpecName.InnerText)
        Catch ex As Exception
            Console.WriteLine("Not Found!")
        End Try
    Next fri
    Console.WriteLine()
    Console.Write("Press enter to continue...")
    Console.ReadLine()
End Sub

End Module

The problem I'm having is that it returns nothing for SelectSingleNode. I've read a lot about using to namespace manager but still haven't gotten it to work.

I have test the xpath using XPath Visualizer and it select the correct node but the vb code can't find it. I'd prefer to use xpath like this because the position of this element might not always be the same and it might not be included at all.