UserControl is "Nothing"?

I am trying to pass one of three different kinds of UserControls into the below SubProcedure and based on the value of the "testType" parameter, the "uc" will get set accordingly. My problem, however, is that the value of "uc" is Nothing when it enters the Try Catch even though it was assigned as a "userLoad", "userCreep" or "userRepeat" UserControl. How can I capture the appropriate UC when passed in?


    Private Sub ValidateLoadEnvironmentValues(uc As UserControl, testType As String)

        Select Case testType
            Case "Load"
                uc = DirectCast(uc, userLoad)
            Case "Creep"
                uc = DirectCast(uc, userCreep)
            Case "Repeat"
                uc = DirectCast(uc, userRepeat)
        End Select

            EH.ErrorMessage = String.Empty

            GetEnvironmentReadings(uc, testType)

            If EH.ErrorMessage = String.Empty Then
            End If


        Catch ex As Exception
            EH.ErrorMessage = "frmCalibration_3/ValidateLoadEnvironmentValues() - " & ex.Message & "...Contact Engineering!" & "~E"
        End Try
    End Sub

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Mike TomlinsonHigh School Computer Science, Computer Applications, and Mathematics TeachersCommented:
What does "GetEnvironmentReadings()" do?  Lines like this "uc = DirectCast(uc, userLoad)" don't actually the type of "uc".  It's still a generic UserControl when you pass it.  If Nothing is the problem, it is most likely getting passed in as Nothing...
BlakeMcKennaAuthor Commented:
It actually references several controls from within the "uc" and then makes another call to a function. The signature parameter "uc" actually does contain a valid UserControl instance .
Mike TomlinsonHigh School Computer Science, Computer Applications, and Mathematics TeachersCommented:
I don't see the point of your ValidateLoadEnvironmentValues() sub, as all it really does is pass the parameters on to GetEnvironmentReadings().  You could do all of this inside of GetEnvironmentReadings() directly...

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BlakeMcKennaAuthor Commented:
I know where your coming from Mike...and makes sense in a normal situation. However, ValidateLoadEnvironmentValues is a SubProcedure that is the object of an "AddressOf" in the dynamic creation of the UserControls. Anyway, I think I figured it out!
BlakeMcKennaAuthor Commented:
Thanks for the input Mike!
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Visual Basic.NET

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