ارور executenonquery connection property has not been initialized

[omidpa2]

کل کد من
Imports System.Data.SqlClient
Public Class Form1
Dim fgsdgsf As New SqlConnection("Data Source=OMID-PC\SQLEXPRESS;Initial Catalog=omid;Integrated Security=True")
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.OmidTableAdapter.Fill(Me.OmidDataSet.omid)
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Try
fgsdgsf.Open()
Dim str1 As New SqlCommand("INSERT INTO omid(user_name) values ('" & TextBox1.Text & "')")
str1.ExecuteNonQuery()
Catch ex As Exception
MsgBox(ex.Message())
End Try
fgsdgsf.Close()
End Sub
End Class

وقتی یه کلمه مینویسم داخل تکست باکس و رو دکمه کلیک میکنم این ارور رو میده
executenonquery connection property has not been initialized:گریه:

[omidpa2]

باید آخر کامند اسم کانکشن هم نوشته بشه!
تو این مثال باد کد به شکل زیر در بیاد!
Dim str1 As New SqlCommand("INSERT INTO omid(user_name) values ('" & TextBox1.Text & "')",fgsdgsf)