LDAP connection working for some applications but not others

I have a server which has LDAP properly configured on it .. its IP is 172.19.50.121 … Now I have other machines on the same network, and if I use an LDAP browser such as Softerra LDAP Administrator or Sysinternals Active Directory Explorer, then I can connect with LDAP and browse it with no problems ..

I am now developing in Lombardi Teamworks (BPM software), and am giving it the following credentials to connect to this same LDAP, but I keep getting the Connection refused: connect exception/error .. The details I'm giving it are the following, which are the same details which worked with the above mentioned tools:

host=172.19.50.121
port=389
login=CN=ldapconntest,CN=Users,DC=sag002dev,DC=root
password=ahmad

The error Connection refused: connect normally occurs when you've specified an incorrect port, which is actually closed on the target machine .. But in this case, port 389 is correct because that is the port I specify when I connect using Softerra LDAP Administrator … But, if I try to telnet like this:

telnet 172.19.50.121 389, it does not connect through, which could mean its closed ? … So there's conflicting information here :/ ..

So I'm confused as to where is the problem !? 🙁