Could some one help me with understanding why this is erroring and what I can do to fix it? I tried leaving it out, but everytime I try to use the add-in it just crashes.

This is taken directly from the Solidworks API Help, but there is no explenation is swdocPART is a place holder, or if it is different in newer versions of Visual Studio.

And I am at a loss on how to fix this, nor can I locate any posts really covering this.

Imports SolidWorks.Interop.sldworks
Imports SolidWorks.Interop.swconst
Imports SolidWorks.Interop
 Module OpenPrt
    Dim swApp As SldWorks
    Dim swModel As ModelDoc2
    Dim swSelMgr As SelectionMgr
    Dim swDocSpecification As DocumentSpecification
    Dim sName As String
    Dim longstatus As Long, longwarnings As Long
    Dim Control1 As UserControl1
    Dim sLocation As String
    Sub OpenStrtPrt()
        swApp = New SldWorks
        sLocation = Control1.StartParts1.SelectedValue
        swDocSpecification = swApp.GetOpenDocSpec(sLocation)
        sName = swDocSpecification.FileName
        swDocSpecification.DocumentType = swDocPART
        swDocSpecification.ViewOnly = False
        swDocSpecification.Silent = True
        swModel = swApp.OpenDoc7(swDocSpecification)
        longstatus = swDocSpecification.Error
        longwarnings = swDocSpecification.Warning
    End Sub
End Module