Need Help Inserting Data Into Table With Sql Insert Into Using Textbox Values

the error message I get is

{"Object reference not set to an instance of an object."}

and it points to <  Tickr As String = CType(FindControl("TickerTextbx"), TextBox).Text >   

 this is my code":

 Protected Sub TickMastBtn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles TickMastBtn.Click

REM Collect variablesDim Tickr As String = CType(FindControl("TickerTextbx"), TextBox).Text

Dim Comp As String = CType(FindControl("CoTextbx"), TextBox).TextDim Exch As String = CType(FindControl("ExchTextbx"), TextBox).Text

REM Create connection and command objectsDim cn As New SqlConnection("Data Source=.SQLEXPRESS;AttachDbFilename=C:Program FilesMicrosoft SQL ServerMSSQL.1MSSQLDataVTRADE.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True")Dim cmd As New SqlCommand

cmd.Connection = cn

REM Build our parameterized insert statementDim sql As New StringBuilder

sql.Append("INSERT INTO TickerMaster ")sql.Append("(Ticker,Company,Exchange,) ")sql.Append("VALUES (@Tickr,@Comp,@Exch,)")

cmd.CommandText = sql.ToString

REM Add parameter values to command

REM Parameters used to protect DB from SQL injection attacksWith cmd.Parameters

.Add("Tickr", SqlDbType.Int).Value = Tickr.Add("Comp", SqlDbType.VarChar).Value = Comp

.Add("Exch", SqlDbType.VarChar).Value = Exch

End With

REM Now execute the statement

cn.Open()

cmd.ExecuteNonQuery()

cn.Close()

End Sub