Error - Conversion failed when converting date and/or time

Question

Hi

 

SqlCommand cmd = new SqlCommand("INSERT INTO [Period] (Date1,Date2) VALUES('" + @Date11 + "','" + @Date12 + "')", con);

cmd.Parameters.AddWithValue("@Date11", txt_Date11.Text.Trim());
cmd.Parameters.AddWithValue("@Date12", txt_Date12.Text.Trim());

Thanks