Directory creation not working in Marshmallow Android

public class MyDevIDS extends AppCompatActivity {

        private static final int REQUEST_RUNTIME_PERMISSION = 123;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            if (CheckPermission(MyDevIDS.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
                // you have permission go ahead
                createApplicationFolder();
            } else {
                // you do not have permission go request runtime permissions
                RequestPermission(MyDevIDS.this, Manifest.permission.WRITE_EXTERNAL_STORAGE, REQUEST_RUNTIME_PERMISSION);
            }
        }

        @Override
        public void onRequestPermissionsResult(int permsRequestCode, String[] permissions, int[] grantResults) {

            switch (permsRequestCode) {

                case REQUEST_RUNTIME_PERMISSION: {
                    if (grantResults.length > 0
                            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                        // you have permission go ahead
                        createApplicationFolder();
                    } else {
                        // you do not have permission show toast.
                    }
                    return;
                }
            }
        }

        public void RequestPermission(Activity thisActivity, String Permission, int Code) {
            if (ContextCompat.checkSelfPermission(thisActivity,
                    Permission)
                    != PackageManager.PERMISSION_GRANTED) {
                if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
                        Permission)) {
                } else {
                    ActivityCompat.requestPermissions(thisActivity,
                            new String[]{Permission},
                            Code);
                }
            }
        }

        public boolean CheckPermission(Context context, String Permission) {
            if (ContextCompat.checkSelfPermission(context,
                    Permission) == PackageManager.PERMISSION_GRANTED) {
                return true;
            } else {
                return false;
            }
        }
    }