Leads conversion window does not open when clicking convert Lead

[phongkni]

I think I configured it correctly
example:
- My system uses a firewall, I have configured the Reverse Proxy when I access port 80 and 443 from network external, then return to the crm local server (example: 192.168.3.20)
- configured dns domain: domain.com
Host-----Type------Value-------------TTL
crm------A---------"Ip firewall"-------3600
- File config.inc.php
$site_URL = 'http://crm.domain.com';
All normal access only convert leads is problematic