Argument not specified for parameter x of Private Function x(x As String) As String

[Modulus]

I'm getting this error in my VB.Net application:

Argument not specified for parameter 'strFileName' of 'Private Function GetMD5String(strFilename As String) As String

when trying to use a function called GetMD5String() in a Timer1_Tick sub.


I'm using this code:

Private Function GetMD5String(ByVal strFilename As String) As String

        Dim cMD5 = Security.Cryptography.MD5.Create
        Dim bytHash As Byte()
        Dim sb As New System.Text.StringBuilder
        Dim scanbox As New TextBox
        scanbox.Text = My.Computer.FileSystem.ReadAllText("viruslist.txt").ToString
        Me.OpenFileDialog1.FileName = strFilename

        Using cStream As New IO.FileStream(strFilename, IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.Read)

            bytHash = cMD5.ComputeHash(cStream)
        End Using

        For Each c In bytHash
            sb.Append(c.ToString("X2"))
        Next

        If scanbox.Text.Contains(sb.ToString) Then
            TextBox1.Text = (strFilename)
            Me.OpenFileDialog1.FileName = strFilename
            Detect.ShowDialog()
            WriteToLog("Malicious exploit detected.")
            Quarantinevb.ListBox1.Items.Add(strFilename)
        End If

        Return sb.ToString



    End Function

and this code for Timer1_Tick

 Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        RefreshList()
        Timer1.Enabled = False 'Stops the timer
        Timer1.Enabled = True
        GetMD5String()
    End Sub

Why is GetMD5String() throwing me this error?