oracle bulkcopy from vb.net databale - vb.net

Question

I am loading the CSV file to vb.net datatable .
then I am using Bulk copy command to write to database.
The problem is if one date cell in the data table is empty, i am receiving
ORA:-01840 input value not long enough for date format.
How to resolve this.
Public Class Form1
Dim cn As New OracleConnection("Data Source =(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP)(HOST = ipaddressofserver)(PORT = portofserver))(CONNECT_DATA =(SERVER = DEDICATED)(SERVICE_NAME = oracleservicename)) ) ; User Id=useridofdb;Password=passwordofdb")
cn.Open()
MsgBox("connection opened")
Dim dt As DataTable = ReadCSV("D:\test.csv")
DataGridView1.DataSource = dt
Try
Dim _bulkCopy As New OracleBulkCopy(cn)
_bulkCopy.DestinationTableName = "TEST_TABLE"
_bulkCopy.BulkCopyTimeout = 10800
_bulkCopy.WriteToServer(dt)
cn.Close()
cn.Dispose()
cn = Nothing
MsgBox("Finished")
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Function ReadCSV(ByVal path As String) As System.Data.DataTable
Try
Dim sr As New StreamReader(path)
Dim fullFileStr As String = sr.ReadToEnd()
sr.Close()
sr.Dispose()
Dim lines As String() = fullFileStr.Split(ControlChars.Lf)
Dim recs As New DataTable()
Dim sArr As String() = lines(0).Split(","c)
For Each s As String In sArr
recs.Columns.Add(New DataColumn())
Next
Dim row As DataRow
Dim finalLine As String = ""
For Each line As String In lines
row = recs.NewRow()
finalLine = line.Replace(Convert.ToString(ControlChars.Cr), "")
row.ItemArray = finalLine.Split(","c)
recs.Rows.Add(row)
Next
Return recs
Catch ex As Exception
Throw ex
End Try
End Function
End Class