We would need to know where the error is being reported, but first, please do no do it like that: it is an invitation to damage or destruction of your database. Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.
str = "Update bxs_tbl set SldID = @SID, DateReport = @DR" where BxsNo = @BXNO
cmd.Connection = cn
cmd.CommandType = CommandType.Text
cmd.CommandText = str
cmd.Parameters.AddWithValue("@SID", txtSLD_ID.Text)
cmd.Parameters.AddWithValue("@DR", dtpReport.Value)
cmd.Parameters.AddWithValue("@BXNO", txtbxsno.Text)
And so on.
It may also solve your problem...or at least make it easier to see.
"I populated this form from listview of another form and it work well. The error occured when I click the update button I'm a beginner in vb.net"
It may "work well" - or appear to, but the fact remains that I could delete your database just but typing into a text box and pressing the "update" button. That is what an SQl Injection Attack is all about. If you are using this type of code in other places, then they are at risk as well. Google for "bobby tables" if you don't believe me, and trust me on this - your best mate will try this "for a laugh" on your database if you give him a chance.