Input string was not in a correct format. mscorlib

[Exceter]

ex.Message = Input string was not in a correct format. ex.Source = mscorlib

at the following line I have that error message,
what that problem is ??
Dim GetRow As DataRow = DataSet99.Tables("Documents").Rows.Find(searchPart)

Private Sub Search_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Search.Click
          If IsValid Then
              Try
                  SqlConnection1.Open()
                  Dim searchPart As String = txtName.Text
                  Dim DataAdapter1 As New SqlClient.SqlDataAdapter("Select * From Documents", SqlConnection1)
                  Dim Command As New SqlClient.SqlCommandBuilder(DataAdapter1)                        Dim DataSet99 As New DataSet
                  DataSet99.Clear()
                  DataAdapter1.Fill(DataSet99, "Documents")
                    Dim keys(1) As DataColumn
                  keys(0) = DataSet99.Tables("Documents").Columns("id_doc")
                  DataSet99.Tables("Documents").PrimaryKey = keys
                    'Dim NameS = "id_doc ='" & searchPart & "'"                  
                  Dim GetRow As DataRow = DataSet99.Tables("Documents").Rows.Find(searchPart)
                    txtInNum.Text = GetRow("cod_int")
                  txtExNum.Text = GetRow("cod_ext")
                  SqlConnection1.Close()
              Catch ex As Exception
                  ErrorMsg.Text = ex.Message & " " & ex.Source
                  ErrorMsg.Visible = True
              End Try
          End If
      End Sub

[alexey_1979]

at the following line I have that error message,
what that problem is ??

The problem is your searchPart is not correct. You should pass to find method the primary key value. For example

table.Rows.Find(10)

[Exceter]

The problem is your searchPart is not correct. You should pass to find method the primary key value.

In my code I have a primary key, do not why - now that code works

I made no changes, but the code now works.