Problem with LDAP over SSL

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LDAP

Hi everybody, I'm working on a project and connect to LDAP Server to verify user.
When setting LDAP Server I have a problem:

I used ldp.exe to test connection:
I can connect to LDAP over SSL (port 636) when I run ldp.exe on server (on window server, ldp.exe and LDAP Server are in the same computer).

But when run ldp.exe on Windoww 7, I only connect to LDAP server by port 389 but over SSL (port 636) is failed (return 0x51)

What's wrong on my server? Help me please!
And thanks so much...