Does the addon domain grp3.tk appear in cPanel on the addon domains page? If not, try adding it again. If it adds successfully, wait 12 hours and test. If you receive an error message when adding the domain, stating that "the domain already exists the apache configuration", please go to Subdomains and add the subdomain grp3.ahmedsuror.tk to the subdomains list. Then go check the addon domains list again to see if the addon domain has appeared. If it appears after doing this, wait 12 hours and see if it works. If it still does not appear, let me know and I'll take a look at it further.