Private Sub chkITRelated_AfterUpdate()
    Dim stDocName As String
    Dim stLinkCriteria As String
    Dim intAnswer As Integer
    Dim strSQL As String
    stDocName = "frmITRelated"
    stLinkCriteria = "[Barcode]=" & Me![Barcode]
    
If chkITRelated.Value = True Then
Me.btnEditITData.Visible = True
    If DCount("*", "tblITRelated", stLinkCriteria) = 0 Then
        intAnswer = MsgBox("The barcode was not found!" & vbCrLf & "Would you like to add it to the IT Related table now?", vbExclamation + vbYesNo, "Error!")
        If intAnswer = vbYes Then
            strSQL = "INSERT INTO tblITRelated([Barcode])" & "VALUES ([Barcode]);"
            DoCmd.SetWarnings False
            DoCmd.RunSQL strSQL
            DoCmd.SetWarnings True
            MsgBox "The barcode has been added!", vbInformation, "Great Success!"
            Response = acDataErrAdded
            DoCmd.OpenForm stDocName, , , stLinkCriteria
        ElseIf intAnswer = vbNo Then
            MsgBox "Clearing IT Related checkbox...", vbInformation, "Oh noes!"
            chkITRelated.Value = False
            Response = acDataErrContinue
        End If
    'ElseIf
        'DoCmd.OpenForm stDocName, , , stLinkCriteria
    End If
Else
Me.btnEditITData.Visible = False
End If
End Sub

MsgBox if statement

VB.NET