Error: Cannot attach empty file in GMAIL app using File provider

I am trying to attach a pdf file in gmail app. I have read this and this (applied solution) I am trying as;

public static void attachFile(Context ctx) {    String TAG = "Attach";    File documentsPath = new File(ctx.getFilesDir(), "documents");    Log.i(TAG,"documentsAbsolutePath Output");    Log.i(TAG, documentsPath.getAbsolutePath().toString());    File file = new File(documentsPath, "sample.pdf");    if ( file.exists() ) {        Toast.makeText(ctx, "Exits", Toast.LENGTH_LONG).show();    }else{        Toast.makeText(ctx, "Not Exist", Toast.LENGTH_LONG).show();    }    Log.i(TAG,"file Output");    Log.i(TAG, file.toString());    Log.i(TAG, String.valueOf(file.length()));    Uri uri = FileProvider.getUriForFile(ctx, "com.example.fyp_awais.attachfiletest2.fileprovider", file);    Log.i(TAG,"URI Output");    Log.i(TAG,uri.toString());    Intent intent = ShareCompat.IntentBuilder.from((Activity) ctx)            .setType("application/pdf")            .setStream(uri)            .setChooserTitle("Choose bar")            .createChooserIntent()            .addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);    ctx.startActivity(intent);}

Outputs

documentsAbsolutePath Output/data/data/com.example.fyp_awais.attachfiletest2/files/documents file Output/data/data/com.example.fyp_awais.attachfiletest2/files/documents/sample.pdf 0 URI Output content://com.example.fyp_awais.attachfiletest2.fileprovider/pdf_folder/sample.pdf

Menifest

<provider    android:name="android.support.v4.content.FileProvider"    android:authorities="com.example.fyp_awais.attachfiletest2.fileprovider"    android:exported="false"    android:grantUriPermissions="true"><meta-data        android:name="android.support.FILE_PROVIDER_PATHS"        android:resource="@xml/filepath" /></provider>

FilePath.xml

<?xml version="1.0" encoding="utf-8"?><PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"><paths xmlns:android="http://schemas.android.com/apk/res/android"><files-path name="pdf_folder" path="documents/"/></paths></PreferenceScreen

A pdf file is saved in Galaxy Core Prime\Phone\documents. (file size: 53.7KB)

But it gives

Cannot attach empty file.

I am confused with folder-name in this line <files-path name="pdf_folder" path="documents/"/>. The file is in the \Phone\documents. Then why folder name?

Edit 1

Tried to replace setType(application/pdf) with setType("message/rfc822") But did not work. Any help?