How can I execute cmd commands by vb.net?

Question

I recently building codes for cmd commands by vb.net. It cannot work by just popping up the same form. I hope that someone can fix it.

Imports System.IO
Public Class Form1
    Private Sub Execute_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Execute.Click
        Result.Text = RunCmd(Command.Text)
    End Sub

    Private Function RunCmd(ByVal cmd As String) As String
        Dim p As Process = New Process
        With p.StartInfo
            .FileName = "cmd.exe"
            .Arguments = "/c " + cmd
            .UseShellExecute = False
            .RedirectStandardInput = True
            .RedirectStandardOutput = True
            .RedirectStandardError = True
            .CreateNoWindow = True
        End With
        p.Start()
        'p.StandardInput.WriteLine(command);
        'p.StandardInput.WriteLine("exit");
        Dim reader As StreamReader = p.StandardOutput
        Dim output As String = reader.ReadToEnd()
        Return output
    End Function
End Class

I expect that I can run the command in the textbox. But it can't.