if statement executing itself instead of others

I have a code here that, each time I run it, only the if statement which states "All fields are required" works but NOT ONLY when it must be called, it actually runs in place of the others. So whatever I do even when all the fields are complete, I have "All fields are required" as an alert message. Here is the code, all help is appreciated, thank you in advance.

@IBAction func registerButtonTapped(_ sender: AnyObject) {

    let userEmail = ""
    let userPassword = ""
    let userRepeatPassword = ""



    // Check for empty fields


    if (userEmail.isEmpty || userPassword.isEmpty || 
userRepeatPassword.isEmpty)
    {
        // Display Alert Message
        displayMyAlertMessage(userMessage:"All fields are required")
        return
    }

    //Check if passwords match
    if (userPassword != userRepeatPassword)
    {
        // Display an alert message
        displayMyAlertMessage(userMessage:"Passwords do not match")
        return
    }


    // Store data
    UserDefaults.standard.set(userEmail, forKey:"userEmail")
    UserDefaults.standard.set(userEmail, forKey:"userPassword")
    UserDefaults.standard.synchronize()


    // Display alert message with confirmation
    _ = UIAlertController(title:"Alert", message:"Registration is 
successfull. Thank you!", 
preferredStyle:UIAlertControllerStyle.alert);

    _ = UIAlertAction(title:"Ok", style:UIAlertActionStyle.default)
    {
        action in
        self.dismiss(animated: true, completion:nil)
    }



 }


func displayMyAlertMessage(userMessage:String)
{

let myAlert = UIAlertController(title:"Alert", message: userMessage, 
preferredStyle:UIAlertControllerStyle.alert);


let okAction = UIAlertAction(title:"Ok", 
style:UIAlertActionStyle.default, handler:nil)

myAlert.addAction(okAction)

self.present(myAlert, animated:true, completion:nil)


}


}