error adding parameters to sql command in VB quickfix

i tried passing the parameter pdata which needs to b a varchar from a textbox and get the error :

Method not found: 'Void System.Data.SqlClient.SqlParameterCollection.Rollback(System.String)'.

heres my code :

Protected Sub changeNum_Click(sender As Object, e As EventArgs) Handles changeNum.Click

    Dim retValue As Integer
    Dim connection As SqlConnection
    connection = New SqlConnection("Data Source=151-rsS\SQLEXPRESS;Initial Catalog=easyDb;Integrated Security=SSPI; ")
    Dim Command = New SqlCommand("UPDATE mytable Set pdata = @value1", connection)

    Command.Parameters.AddwithValue("@value1", htgtextbox.Text)
    connection.Open()
    retValue = Command.ExecuteNonQuery()
    connection.Close()

End Sub