Error recognizing dataBinding class android

Question

in one of my projects I have started to implement dataBinding in the main activity by separating the data in a class called view, in another class called viewModel and in the model class. Using these classes and the dataBinding, the application has been compiled correctly, but when I put the classes in different packages to follow the MVVM architecture, the self-generated class named ActivityLoginBinding does not recognize the class that is inside the ViewModel package. I have already done searches of different projects to see if it was my mistake at syntax level, but they are well written. I have also noticed that all the projects are divided into different packages and work correctly. Any idea why this happens and how could it be solved? Thank you.

my xml

<?xml version="1.0" encoding="utf-8"?>

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>
        <variable
            name="student3"
            type="com.juan97.prueba.ViewModel.Student3ViewModel"/>
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".View.MainActivity">

        <TextView
            android:layout_marginTop="50sp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:hint="@{student3.hint1}"/>

        <TextView
            android:layout_marginTop="50sp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:hint="@{student3.hint2}"/>

    </LinearLayout>


</layout>

gradle module app

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.juan97.prueba"
        minSdkVersion 19
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    dataBinding {
        enabled = true
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

Different packages I have:

compile error