I personaly havent used the Amazon Web ServicesAmazon Web Services before (i went for the self hosted option) however I think your problem might be either down to one of three things.
Firstly: The URL that your using to connect;
If your connecting from your home computer then you will need to replace the "localhost" part of the URL with either the IP address or the "public domain name",
if you were asigned one, that points to your A.W.S box. However if your remoting e.g "desktop remote connection, ssh e.t.c" in to the box and are using the box's own browser then "localhost" is fine!
Secondly: by default the hostmanager's port is usally 8088, however as i stated erlier i have never used A.W.S before so they may have changed the default port, you could try and connect using that port and see if it makes any differance.
Thirdly: you may want to check the running services on your box to make sure that both "Wowza Streaming Engine" and "Wowza Streaming Engine Manager" have been started/are currenly running, fomr what i have previously read on the forums i do beleive that there have been instances that when the A.W.S server has been rebooted some times it dosent auto start thease servies hence the suggestion.
Other than those things then im afraid im swimming in waters that are far to deep, so ill happily pass this one to a more experiances member.
Hope this is of some help, if not i hope your able to figure the problem out!
Ahh my apologies i Mis understood what you were saying the your origional post.
This appears to be a problem with the Engine Manager talking to the Engine its self, unfortunatly with out delving through config files/firewalls setups e.t.c or haivng direct access tot he box im of not mutch use here.
Your best bet would be to open up a support ticket directly with Wowza to do this follow the instructions below:
Support Request Instructions:
For Wowza email support requests, be sure to provide the following information with your request to
firstname.lastname@example.org. To find this information, click the
Server tab in Wowza Streaming Engine Manager, and then click
About in the contents pane.
Wowza Streaming Engine version and build number
Last four digits of license key
Platform, operating system, and Java version on which Wowza Streaming Engine is running
Detailed problem description that includes:
URL of tutorial or instructions being used
Player technology being used (Adobe Flash, Microsoft Silverlight, iOS device, set-top box, etc.)
Live encoder/IP camera manufacturer/version and exact encoding settings (live streaming only)