Is the Distributes Web Server (DWS) configured to access this ESXi system ? Please note that when OMSA VIB is installed on ESXi, it does not lay down the web component. A DWS needs to be installed on another system and point it to the ESXi system.
Here is an article on the installation and configuration of Dell OpenManage Server Administrator With VMware ESXi 5.1:
deinfotech.blogspot.com/.../install-dell-openmanage-server.html
Thanks,
Raj Shresta