I can't login by Added Help Desk Technicians

I can't login by Added Help Desk Technicians

Hi,
I am using ADManager Plus.
I add new Help Desk Technicians from my AD.

But when I try login to ADManager control Panel it show me this error:

Username: mydomain\myuser
Password: mypassword

For input string: "unlimited"

please help me what should I do?
              New to ADManager Plus?

                New to ADSelfService Plus?