How do I set up reverse proxy in Apache on a Slackware 14.2 Server?

Zabbix is accessed through the link myu.com/zabbix, and is restricted by LDAP authentication; Now, I want Grafana to be accessed by myu.com/grafana, and since Grafana runs on a server itself, on port 3000, I need to do the reverse proxy to go through LDAP authentication as well.

In /etc/httpd/httpd.conf I enabled the following modules:

.mod_proxy;
.mod_proxy_http;
.mod_proxy_balancer (you may not even need to);
.mod_lbmethod_byrequests;
.mod_slotmem_shm;

I also had to uncomment the line:

#Include /etc/httpd/extra/httpd-vhosts.conf

And in /etc/httpd/extra/httpd_vhosts.conf I left it like this:

Code:<VirtualHost *:443>
ServerAdmin admin@myu.com
ServerName myu.com
ErrorLog "/var/log/httpd/error_log"
CustomLog "/var/log/httpd/access_log" common

<Location /grafana>
ProxyPass "http://192.168.6.3:3000/"
ProxyPassReverse "http://192.168.6.3:3000/"

SSLRequireSSL
AuthType basic
AuthBasicProvider ldap
AuthName "Restricted access"
AuthLDAPBindDN cn=apacheldap,ou=DSA,dc=myu,dc=com
AuthLDAPBindPassword xxxxxxxx
AuthLDAPURL ldap://ldap2.myu.com:389/ou=people,dc=myu,dc=com?uid?one TLS
AuthLDAPGroupAttribute memberUid
AuthLDAPGroupAttributeIsDN off
Require ldap-group cn=crsintranetrestrita,ou=groups,dc=myu,dc=com
</Location>
ProxyPreserveHost On
</VirtualHost>However, when trying to access any website after that, the message appears:

ssl_error_rx_record_too_long

I just comment on "#Include /etc/httpd/extra/httpd-vhosts.conf" again and the error goes away, but then I am left without grafana.myu.com in the hopeless way.

What can be wrong with these settings for reverse proxy?