Problem on Update Acsess database And add or do over one time database

[almusamim]

hi every one,

please i have some problems on my first project in vb.net

1st on update the row on acsess database the wronge message is :
Conversion from string "UPDATE [employee] SET [efullname" to type 'Double' is not valid.

but my efullname data is also string
code of update

            'cmd.CommandType = CommandType.Text = "UPDATE [employee] SET efullname=@efullname, eusername=@eusername, epassword=@epassword, emobile=@emobile, eemail=@eemail, esalary=@esalary, startworkingdate=@stdate, visaenddate=@nddate WHERE eusername = '" & usernameList.Text & "' "
            'cmd.Parameters.AddWithValue("@efullname", TextBox4.Text)
            'cmd.Parameters.AddWithValue("@eusername", TextBox1.Text)
            'cmd.Parameters.AddWithValue("@epassword", TextBox2.Text)
            'cmd.Parameters.AddWithValue("@emobile", TextBox3.Text)
            'cmd.Parameters.AddWithValue("@eemail", TextBox5.Text)
            'cmd.Parameters.AddWithValue("@esalary", TextBox6.Text)
            'cmd.Parameters.AddWithValue("@stdate", DateTimePicker1.Value.ToString("dd/MM/yyyy"))
            'cmd.Parameters.AddWithValue("@nddate", DateTimePicker2.Value.ToString("dd/MM/yyyy"))
            If con.State = ConnectionState.Open Then con.Close()
            con.Open()


            Try

                cmd.ExecuteNonQuery()
                cmd.Dispose()
                con.Close()
End try

2nd problem When i add or do any process one time its ok
but when i add or any procsess again in same window thats going to erorr message on Opening conniction code ??

Thanks

[almusamim]

Sorry

For Update my post

I'm Waiting any reply