Have you looked at Release Notes:
http://docs.blackberry.com/en/admin/...ease_Notes.pdf
Relating to your problem, it says:
Functional changes
Installation
You install the tool using a Microsoft® Windows® Installer file with the following name:
brk-besuseradmin<platform_identifier><version>.msi
where
<platform_identifier> is <x> for Microsoft® Exchange or <d> for IBM® Lotus®Domino®
<version> is the release bundle
Example: brk-besuseradmind5.0.0.51.msi
Authentication and authorization
In BlackBerry Enterprise Server version 5.0, the models for authentication (login) and authorization (roles or capabilities) for administration are different from the models that were used in previous versions. Roles or capabilities that are based on database user accounts are not supported.
In the BlackBerry Enterprise Server User Administration Tool version 5.0, you can use the following parameters interchangeably:
•“-username” or “-sqluser” (authentication user name)
•“-password” or “-sqlpass” (authentication password)
The tool uses the values associated with these options for the authentication and authorization models that are supported in the BlackBerry Enterprise Server version 5.0. The tool does not does not support Microsoft® SQL Server® authentication or roles or capabilities that are defined on the Microsoft SQL Server database engine.
For information about authentication credentials, including syntax, storing credentials in and extracting credentials from the Windows registry, and use cases, visit
BlackBerry - Manuals and Guides for Administrators to read the BlackBerry Enterprise Server User Administration Tool Administration Guide.