Sitemap.xml giving error when access

Server : Shared Bigrock
Trying to Rewrite sitemap.php to sitemap.xml
But when going to access (Showing blank in firefox and HTTP ERROR 500 in chrome).

Note : Working fine on local server (xampp).

My HTACCESS Code is as below

Options +FollowSymLinks -MultiViews
RewriteEngine on
# ensure www.
RewriteCond %{HTTP_HOST} !^www. (NC)
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} (L,R=301)
# ensure https
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteCond %{HTTPS} off
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} (L,R=301)
RewriteRule places-(.*).php$ places.php?page=$1 (NC,L)
RewriteRule blog-(.*).php$ blog.php?page=$1 (NC,L)
Rewriterule sitemap.xml$ sitemap.php (L)
Rewriterule sitemap1.xml$ sitemap1.php (L)
Rewriterule sitemap2.xml$ sitemap2.php (L)

Code (markup):

I am using same code to one of our website at VPS and working fine but not at shared server. Please guide me that what i am missing here.

I am trying to find error and put code also at sitemap.php

ini_set('display_errors', 1);
header('Content-Type: text/xml');


But seems like its not entering to page ….. because showing either blank page or 500 error only.