Android Version on Phone : 6.0.1 ( Android marshmallow ) 
Android target SDK Version 25
I Calling the ActivityCompat.requestPermissions in Android button but doesn't show dialog to Procced it
Button
printrequest.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View arg0) {
        try{
            verifyStoragePermissions(SickFragmentId.this);
        }
        catch(Exception e ){
            Log.e("LoginActv: Save Block", e.getMessage());
            e.getStackTrace();
        }
        String req = textViewReqNo.getText().toString();
        String name = Name.getText().toString();
        String branch = Branch.getText().toString();
        String departement_position = Departement_Position.getText().toString();
        String status = Status.getText().toString();
        String description = Description.getText().toString();
        String type = Status.getText().toString();
        String date = Date.getText().toString();
        Intent showId = new Intent(SickFragmentId.this, print.class);
        startActivity(showId);
    }
});
And i put the code in Print.java
public class print extends Activity {
    private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };
    public static void verifyStoragePermissions(Activity activity) {
        int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);
        Log.e("Permission value", permission + " ");
        if (permission != 1) {
            Log.e("Permission ask", "Asking, permission not granted");
            ActivityCompat.requestPermissions(
                    activity,
                    PERMISSIONS_STORAGE,
                    REQUEST_EXTERNAL_STORAGE
            );
        }
    }
    @Override
    public void onRequestPermissionsResult(int requestCode,  String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 200) {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Log.e("PERResult", "Granted");
                String FILE = Environment.getExternalStorageDirectory().toString()
                        + "/PDF/" + "AldanRIZKISANTOSA.pdf";
                Document document = new Document(PageSize.A4);
                // Create Directory in External Storage
                String root = Environment.getExternalStorageDirectory().toString();
                File myDir = new File(root + "/PDF");
                myDir.mkdirs();
                // Create Pdf Writer for Writting into New Created Document
                try {
                    PdfWriter.getInstance(document, new FileOutputStream(FILE));
                    // Open Document for Writting into document
                    document.open();
                    // User Define Method
                    addMetaData(document);
                    addTitlePage(document);
                } catch (FileNotFoundException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (DocumentException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                // Close Document after writting all content
                document.close();
                Toast.makeText(this, "PDF File is Created. Location : " + FILE,
                        Toast.LENGTH_LONG).show();
            } else {
                Log.e("PERResult", "Denied");
                Toast.makeText(getApplicationContext(), "PERMISSION_DENIED", Toast.LENGTH_SHORT).show();
            }
        }
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
    // Set PDF document Properties
    public void addMetaData(Document document)
    {
        document.addTitle("RESUME");
        document.addSubject("Person Info");
        document.addKeywords("Personal, Education, Skills");
        document.addAuthor("TAG");
        document.addCreator("TAG");
    }
    public void addTitlePage(Document document) throws DocumentException {
        // Font Style for Document
        Font catFont = new Font(Font.FontFamily.TIMES_ROMAN, 18, Font.BOLD);
        Font titleFont = new Font(Font.FontFamily.TIMES_ROMAN, 22, Font.BOLD
                | Font.UNDERLINE, BaseColor.GRAY);
        Font smallBold = new Font(Font.FontFamily.TIMES_ROMAN, 12, Font.BOLD);
        Font normal = new Font(Font.FontFamily.TIMES_ROMAN, 12, Font.NORMAL);
        // Start New Paragraph
        Paragraph prHead = new Paragraph();
        // Set Font in this Paragraph
        prHead.setFont(titleFont);
        // Add item into Paragraph
        prHead.add("RESUME – Name\n");
        // Create Table into Document with 1 Row
        PdfPTable myTable = new PdfPTable(1);
        // 100.0f mean width of table is same as Document size
        myTable.setWidthPercentage(100.0f);
        // Create New Cell into Table
        PdfPCell myCell = new PdfPCell(new Paragraph(""));
        myCell.setBorder(Rectangle.BOTTOM);
        // Add Cell into Table
        myTable.addCell(myCell);
        prHead.setFont(catFont);
        prHead.add("\nName1 Name2\n");
        prHead.setAlignment(Element.ALIGN_CENTER);
        // Add all above details into Document
        document.add(prHead);
        document.add(myTable);
        document.add(myTable);
        // Now Start another New Paragraph
        Paragraph prPersinalInfo = new Paragraph();
        prPersinalInfo.setFont(smallBold);
        prPersinalInfo.add("Address 1\n");
        prPersinalInfo.add("Address 2\n");
        prPersinalInfo.add("City: SanFran. State: CA\n");
        prPersinalInfo.add("Country: USA Zip Code: 000001\n");
        prPersinalInfo
                .add("Mobile: 9999999999 Fax: 1111111 Email: john_pit@gmail.com \n");
        prPersinalInfo.setAlignment(Element.ALIGN_CENTER);
        document.add(prPersinalInfo);
        document.add(myTable);
        document.add(myTable);
        Paragraph prProfile = new Paragraph();
        prProfile.setFont(smallBold);
        prProfile.add("\n \n Profile : \n ");
        prProfile.setFont(normal);
        prProfile
                .add("\nI am Mr. XYZ. I am Android Application Developer at TAG.");
        prProfile.setFont(smallBold);
        document.add(prProfile);
        // Create new Page in PDF
        document.newPage();
    }
}
But the Dialog for permission doesn't show
Before i use ActivityCompat.requestPermissions i have error
java.io.FileNotFoundException: /storage/emulated/0/PDF/Name.pdf (Permission denied)
After i use ActivityCompat.requestPermission i have error
E/Permission value: -1
E/Permission ask: Asking, permission not granted