Databinding does not exist: how to solve it?

I'm working on an Android application with databinding but I've always next error

Error: Package my.package.databinding does not exist.

Here is my build.gradle on project level:

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.2.2'
    }
}
allprojects {
    repositories {
        jcenter()
    }
}
task clean(type: Delete) {
    delete rootProject.buildDir
}

I've also enabled binding in the build.gradle file on module level.

Now my question is, why occurs this error and how could I solve it?

I've tried to search on internet but no general solutions found for the problem I've got.