Adding a table view to a UI View Controller error

I have a storyboard set up with a View controller . the view controller is divided into two halves , one half is a UI date picker and the other is a table view . When I set the view controller as the delegate and datasource , I get the following error

reason: '-[UIViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x7fdb29b4d9e0'

My View controller is defined in the following way

import Foundation
import UIKit

class CustomViewController:  UIViewController , UITableViewDelegate , UITableViewDataSource{

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int{

        return 3;
    }


    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell{

        var sampleCell = tableView.dequeueReusableCellWithIdentifier("cell") as! UITableViewCell

        return sampleCell;

    }



}