Date and month switched

Hi,
The field is a string that is like
04/06/2013 07:18:47 AM

and then I further convert it to be a date, like

cmd.Parameters.Add("@join_dt", SqlDbType.DateTime).Value = Convert.ToDateTime(tb_join_dt.Text.Trim());

while further it is stored in the column with date and month switched, like the following. Why?

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Many Thanks & Best Regards, Hua Min