救命啊！！！救命啊！！！！

我使用oledb去执行oracle的存储过程，提示错误~ 单独执行存储过程没有问题，请问怎么办呀？？

Dim cmdyhlbas As New OleDb.OleDbCommand
Dim cmdparam As New OleDb.OleDbParameter
Dim cmdparam1 As New OleDb.OleDbParameter
Dim cmdparam2 As New OleDb.OleDbParameter
Dim cmdparam3 As New OleDb.OleDbParameter
Dim querystr As String
Dim reader As OleDb.OleDbDataReader
Dim sqlstring As String
cmdyhlbas.Connection = conn
cmdyhlbas.CommandText = "QUERY.BPR_WEBQUERY"
cmdyhlbas.CommandType = CommandType.StoredProcedure


cmdparam = cmdyhlbas.Parameters.Add("flag", 1)
cmdparam.Direction = ParameterDirection.Input
cmdparam.OleDbType = SqlDbType.Int
cmdparam.Size = 6

cmdparam1 = cmdyhlbas.Parameters.Add("userinput", Trim(Session.Item("acct_nbr_97")))
cmdparam1.Direction = ParameterDirection.Input
cmdparam1.OleDbType = SqlDbType.Char
cmdparam1.Size = 12

cmdparam2 = cmdyhlbas.Parameters.Add("usermonth", DropDownList1.SelectedValue)
cmdparam2.Direction = ParameterDirection.Input
cmdparam2.OleDbType = SqlDbType.Char
cmdparam2.Size = 12


cmdparam3 = cmdyhlbas.Parameters.Add("sqlstring", "1")
cmdparam3.Direction = ParameterDirection.Output
cmdparam3.OleDbType = SqlDbType.Char
cmdparam3.Size = 5000




conn.Open()
reader = cmdyhlbas.ExecuteReader //这句出错