text don't appear in viewFlipper

I used viewFlipper to make onboarding screen and tried to add text in every slide, but I don't know how to display it in the activity_slider.

This is the activity_slider:

<ViewFlipper
    android:id="@+id/viewFlipper"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginVertical="100dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <include layout="@layout/slide1" />

    <include layout="@layout/slide2" />

    <include layout="@layout/slide3" />


</ViewFlipper>

and this is the slide1 and the others is the same but with different imgs

<ImageView
    android:id="@+id/titleImage"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="10dp"
    android:src="@drawable/collaborate"/>

<TextView
    android:id="@+id/texttitle"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="50dp"
    android:fontFamily="@font/poppins_bold"
    android:text="@string/heading_one"
    android:textAlignment="center"
    android:textColor="@color/black"
    android:textSize="28dp" />

<TextView
    android:id="@+id/textdeccription"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginHorizontal="30dp"
    android:fontFamily="@font/poppins"
    android:text="@string/desc_one"
    android:textAlignment="center"
    android:textColor="@color/black"
    android:textSize="16dp" />

And here is the onboarding code:

private lateinit var viewFlipper: ViewFlipper
    private lateinit var nextButton: Button
    private lateinit var backButton: Button
    private lateinit var skipButton: Button

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_slider)

        viewFlipper = findViewById(R.id.viewFlipper)
        nextButton = findViewById(R.id.nextbtn)
        backButton = findViewById(R.id.backbtn)
        skipButton = findViewById(R.id.skipButton)

        viewFlipper.setOutAnimation(this, android.R.anim.slide_out_right)
        viewFlipper.setInAnimation(this, android.R.anim.slide_in_left)

        nextButton.setOnClickListener {
            viewFlipper.showNext()
            if (viewFlipper.currentView == viewFlipper.getChildAt(viewFlipper.childCount - 1)) {
                startActivity(Intent(this, SignupActivity::class.java))
            } else {
                viewFlipper.showNext()
            }

        }

        backButton.setOnClickListener {
            viewFlipper.showPrevious()

        }

        skipButton.setOnClickListener {

            val sharedPreferences: SharedPreferences = getSharedPreferences("onboarding_prefs", MODE_PRIVATE)
            sharedPreferences.edit().putBoolean("isFirstTime", false).apply()


            startActivity(Intent(this, SignupActivity::class.java))
            finish()
        }

    }
}

I expected to see the onboarding screen with text, what could I be doing wrong?

i added to the onboarding activity an index and added text that changes based on index number

Onboarding Activity (Onboarding.kt)

 private val slideTexts = arrayOf(
    "Welcome to our app",
    "Discover amazing features",
    "Get started now"
)
private var currentIndex = 0

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_slider)

    viewFlipper = findViewById(R.id.viewFlipper)
    nextButton = findViewById(R.id.nextbtn)
    backButton = findViewById(R.id.backbtn)
    skipButton = findViewById(R.id.skipButton)
    textSlide = findViewById(R.id.textSlide) 

    updateSlideText()

    viewFlipper.setOutAnimation(this, android.R.anim.slide_out_right)
    viewFlipper.setInAnimation(this, android.R.anim.slide_in_left)

    nextButton.setOnClickListener {
        if (currentIndex < viewFlipper.childCount - 1) {
            currentIndex++
            viewFlipper.showNext()
            updateSlideText()
        } else {
            navigateToSignup()
        }
    }

    backButton.setOnClickListener {
        if (currentIndex > 0) {
            currentIndex--
            viewFlipper.showPrevious()
            updateSlideText()
        }
    }

XML Layout (activity_slider.xml)

 <TextView
    android:id="@+id/textSlide"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Welcome to our app"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="@+id/ellipse1"
    app:layout_constraintTop_toBottomOf="@+id/viewFlipper" />