Exit segue doesn't dismiss

[MickaelCruzDB]

I have this error message :
Symphonics Siemens[30998:498802] attempt to dismiss modal view controller whose view does not currently appear. self = <UINavigationController: 0x78e1b480> modalViewController = <Symphonics_Siemens.TechnicalView: 0x7aa7eaa0>

You create this IBAction to avoid this but I still have the problem :

@IBAction func unwindToMainViewController (sender: UIStoryboardSegue){
// bug? exit segue doesn't dismiss so we do it manually...
self.dismissViewControllerAnimated(true, completion: nil)
}