Android webview print

I have created an app that is a webview that opens a web page made in PHP in android as if it were an application, it works perfectly but the problem is that the buttons do not print they work, you give them and they do not do anything and if you go by Google chrome in android they work totally, I do not know if in a webview you can not or you need to import something or create some objteto to be able to print.

The code would be:

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    WebView myWebView = (WebView) findViewById(R.id.myWebView);
    myWebView.loadUrl("la url");
    myWebView.setWebViewClient(new MyWebViewClient());
    WebSettings webSettings = myWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);
}


private class MyWebViewClient extends WebViewClient {

}

public boolean onKeyDown(int keyCode, KeyEvent event) {
    WebView mWebView;
    mWebView = (WebView) findViewById(R.id.myWebView);
    if (event.getAction() == KeyEvent.ACTION_DOWN) {
        switch (keyCode) {
            case KeyEvent.KEYCODE_BACK:
                if (mWebView.canGoBack()) {
                    mWebView.goBack();
                } else {
                    finish();
                }
                return true;
        }
    }
    return super.onKeyDown(keyCode, event);
}

}